diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 913090d..506fbd9 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -95,6 +95,7 @@
     { "gfx",        "Graphics",         ATRACE_TAG_GRAPHICS, {
         { OPT,      "events/mdss/enable" },
         { OPT,      "events/sde/enable" },
+        { OPT,      "events/mali_systrace/enable" },
     } },
     { "input",      "Input",            ATRACE_TAG_INPUT, { } },
     { "view",       "View System",      ATRACE_TAG_VIEW, { } },
diff --git a/include/android/trace.h b/include/android/trace.h
index d9e5d88..99b3f82 100644
--- a/include/android/trace.h
+++ b/include/android/trace.h
@@ -25,6 +25,8 @@
  *
  * These trace events can be collected and visualized using the Systrace tool.
  * For information about using the Systrace tool, read <a href="https://developer.android.com/studio/profile/systrace.html">Analyzing UI Performance with Systrace</a>.
+ *
+ * Available since API level 23.
  */
 
 #ifndef ANDROID_NATIVE_TRACE_H
@@ -40,26 +42,32 @@
 #if __ANDROID_API__ >= 23
 
 /**
- * Returns true if tracing is enabled. Use this signal to avoid expensive computation only necessary
+ * Returns true if tracing is enabled. Use this to avoid expensive computation only necessary
  * when tracing is enabled.
+ *
+ * Available since API level 23.
  */
 bool ATrace_isEnabled();
 
 /**
  * Writes a tracing message to indicate that the given section of code has begun. This call must be
- * followed by a corresponding call to endSection() on the same thread.
+ * followed by a corresponding call to {@link ATrace_endSection} on the same thread.
  *
- * Note: At this time the vertical bar character '|' and newline character '\n' are used internally
- * by the tracing mechanism. If sectionName contains these characters they will be replaced with a
+ * Note: At this time the vertical bar character '|' and newline character '\\n' are used internally
+ * by the tracing mechanism. If \p sectionName contains these characters they will be replaced with a
  * space character in the trace.
+ *
+ * Available since API level 23.
  */
 void ATrace_beginSection(const char* sectionName);
 
 /**
  * Writes a tracing message to indicate that a given section of code has ended. This call must be
- * preceeded by a corresponding call to beginSection(char*) on the same thread. Calling this method
+ * preceeded by a corresponding call to {@link ATrace_beginSection} on the same thread. Calling this method
  * will mark the end of the most recently begun section of code, so care must be taken to ensure
- * that beginSection / endSection pairs are properly nested and called from the same thread.
+ * that {@link ATrace_beginSection}/{@link ATrace_endSection} pairs are properly nested and called from the same thread.
+ *
+ * Available since API level 23.
  */
 void ATrace_endSection();
 
diff --git a/libs/binder/Value.cpp b/libs/binder/Value.cpp
index 2b263ed..a28a618 100644
--- a/libs/binder/Value.cpp
+++ b/libs/binder/Value.cpp
@@ -229,7 +229,7 @@
 #ifdef LIBBINDER_VALUE_SUPPORTS_TYPE_INFO
 const std::type_info& Value::type() const
 {
-    return mContent != NULL
+    return mContent != nullptr
         ? mContent->type()
         : typeid(void);
 }
@@ -306,7 +306,7 @@
 
 #define BEGIN_HANDLE_WRITE()                                                                      \
     do {                                                                                          \
-        const void* t_info(mContent?mContent->type_ptr():NULL);                                   \
+        const void* t_info(mContent?mContent->type_ptr():nullptr);                                \
         if (false) { }
 #define HANDLE_WRITE_TYPE(T, TYPEVAL, TYPEMETHOD)                                                 \
     else if (t_info == internal_type_ptr<T>()) {                                                  \
diff --git a/libs/binder/include/binder/Binder.h b/libs/binder/include/binder/Binder.h
index 3404881..0b60b4e 100644
--- a/libs/binder/include/binder/Binder.h
+++ b/libs/binder/include/binder/Binder.h
@@ -40,13 +40,13 @@
                                     uint32_t flags = 0);
 
     virtual status_t    linkToDeath(const sp<DeathRecipient>& recipient,
-                                    void* cookie = NULL,
+                                    void* cookie = nullptr,
                                     uint32_t flags = 0);
 
     virtual status_t    unlinkToDeath(  const wp<DeathRecipient>& recipient,
-                                        void* cookie = NULL,
+                                        void* cookie = nullptr,
                                         uint32_t flags = 0,
-                                        wp<DeathRecipient>* outRecipient = NULL);
+                                        wp<DeathRecipient>* outRecipient = nullptr);
 
     virtual void        attachObject(   const void* objectID,
                                         void* object,
diff --git a/libs/binder/include/binder/BpBinder.h b/libs/binder/include/binder/BpBinder.h
index 8bd297b..c4c8ba3 100644
--- a/libs/binder/include/binder/BpBinder.h
+++ b/libs/binder/include/binder/BpBinder.h
@@ -47,12 +47,12 @@
                                     uint32_t flags = 0);
 
     virtual status_t    linkToDeath(const sp<DeathRecipient>& recipient,
-                                    void* cookie = NULL,
+                                    void* cookie = nullptr,
                                     uint32_t flags = 0);
     virtual status_t    unlinkToDeath(  const wp<DeathRecipient>& recipient,
-                                        void* cookie = NULL,
+                                        void* cookie = nullptr,
                                         uint32_t flags = 0,
-                                        wp<DeathRecipient>* outRecipient = NULL);
+                                        wp<DeathRecipient>* outRecipient = nullptr);
 
     virtual void        attachObject(   const void* objectID,
                                         void* object,
diff --git a/libs/binder/include/binder/Debug.h b/libs/binder/include/binder/Debug.h
index be0266c..58e2b32 100644
--- a/libs/binder/include/binder/Debug.h
+++ b/libs/binder/include/binder/Debug.h
@@ -31,12 +31,12 @@
 typedef void (*debugPrintFunc)(void* cookie, const char* txt);
 
 void printTypeCode(uint32_t typeCode,
-    debugPrintFunc func = 0, void* cookie = 0);
+    debugPrintFunc func = nullptr, void* cookie = nullptr);
 
 void printHexData(int32_t indent, const void *buf, size_t length,
     size_t bytesPerLine=16, int32_t singleLineBytesCutoff=16,
     size_t alignment=0, bool cArrayStyle=false,
-    debugPrintFunc func = 0, void* cookie = 0);
+    debugPrintFunc func = nullptr, void* cookie = nullptr);
 
 
 ssize_t getBinderKernelReferences(size_t count, uintptr_t* buf);
diff --git a/libs/binder/include/binder/IBinder.h b/libs/binder/include/binder/IBinder.h
index 2e62957..318070a 100644
--- a/libs/binder/include/binder/IBinder.h
+++ b/libs/binder/include/binder/IBinder.h
@@ -132,7 +132,7 @@
      * directly do with it now that it has passed on.)
      */
     virtual status_t        linkToDeath(const sp<DeathRecipient>& recipient,
-                                        void* cookie = NULL,
+                                        void* cookie = nullptr,
                                         uint32_t flags = 0) = 0;
 
     /**
@@ -143,9 +143,9 @@
      * added with that cookie will be unlinked.
      */
     virtual status_t        unlinkToDeath(  const wp<DeathRecipient>& recipient,
-                                            void* cookie = NULL,
+                                            void* cookie = nullptr,
                                             uint32_t flags = 0,
-                                            wp<DeathRecipient>* outRecipient = NULL) = 0;
+                                            wp<DeathRecipient>* outRecipient = nullptr) = 0;
 
     virtual bool            checkSubclass(const void* subclassID) const;
 
diff --git a/libs/binder/include/binder/IInterface.h b/libs/binder/include/binder/IInterface.h
index b61278a..5ec02b1 100644
--- a/libs/binder/include/binder/IInterface.h
+++ b/libs/binder/include/binder/IInterface.h
@@ -96,11 +96,11 @@
             const ::android::sp<::android::IBinder>& obj)               \
     {                                                                   \
         ::android::sp<I##INTERFACE> intr;                               \
-        if (obj != NULL) {                                              \
+        if (obj != nullptr) {                                           \
             intr = static_cast<I##INTERFACE*>(                          \
                 obj->queryLocalInterface(                               \
                         I##INTERFACE::descriptor).get());               \
-            if (intr == NULL) {                                         \
+            if (intr == nullptr) {                                      \
                 intr = new Bp##INTERFACE(obj);                          \
             }                                                           \
         }                                                               \
@@ -135,7 +135,7 @@
         const String16& _descriptor)
 {
     if (_descriptor == INTERFACE::descriptor) return this;
-    return NULL;
+    return nullptr;
 }
 
 template<typename INTERFACE>
diff --git a/libs/binder/include/binder/IMemory.h b/libs/binder/include/binder/IMemory.h
index 15a104f..3099bf5 100644
--- a/libs/binder/include/binder/IMemory.h
+++ b/libs/binder/include/binder/IMemory.h
@@ -72,7 +72,7 @@
 public:
     DECLARE_META_INTERFACE(Memory)
 
-    virtual sp<IMemoryHeap> getMemory(ssize_t* offset=0, size_t* size=0) const = 0;
+    virtual sp<IMemoryHeap> getMemory(ssize_t* offset=nullptr, size_t* size=nullptr) const = 0;
 
     // helpers
     void* fastPointer(const sp<IBinder>& heap, ssize_t offset) const;
diff --git a/libs/binder/include/binder/IPCThreadState.h b/libs/binder/include/binder/IPCThreadState.h
index 245607e..ab68b41 100644
--- a/libs/binder/include/binder/IPCThreadState.h
+++ b/libs/binder/include/binder/IPCThreadState.h
@@ -95,7 +95,7 @@
 
             status_t            sendReply(const Parcel& reply, uint32_t flags);
             status_t            waitForResponse(Parcel *reply,
-                                                status_t *acquireResult=NULL);
+                                                status_t *acquireResult=nullptr);
             status_t            talkWithDriver(bool doReceive=true);
             status_t            writeTransactionData(int32_t cmd,
                                                      uint32_t binderFlags,
diff --git a/libs/binder/include/binder/IServiceManager.h b/libs/binder/include/binder/IServiceManager.h
index 3b23f81..445a072 100644
--- a/libs/binder/include/binder/IServiceManager.h
+++ b/libs/binder/include/binder/IServiceManager.h
@@ -69,7 +69,7 @@
 status_t getService(const String16& name, sp<INTERFACE>* outService)
 {
     const sp<IServiceManager> sm = defaultServiceManager();
-    if (sm != NULL) {
+    if (sm != nullptr) {
         *outService = interface_cast<INTERFACE>(sm->getService(name));
         if ((*outService) != NULL) return NO_ERROR;
     }
diff --git a/libs/binder/include/binder/MemoryDealer.h b/libs/binder/include/binder/MemoryDealer.h
index 60a624c..fe5a31d 100644
--- a/libs/binder/include/binder/MemoryDealer.h
+++ b/libs/binder/include/binder/MemoryDealer.h
@@ -34,7 +34,7 @@
 class MemoryDealer : public RefBase
 {
 public:
-    MemoryDealer(size_t size, const char* name = 0,
+    MemoryDealer(size_t size, const char* name = nullptr,
             uint32_t flags = 0 /* or bits such as MemoryHeapBase::READ_ONLY */ );
 
     virtual sp<IMemory> allocate(size_t size);
diff --git a/libs/binder/include/binder/MemoryHeapBase.h b/libs/binder/include/binder/MemoryHeapBase.h
index ea9b66c..5e0a382 100644
--- a/libs/binder/include/binder/MemoryHeapBase.h
+++ b/libs/binder/include/binder/MemoryHeapBase.h
@@ -52,7 +52,7 @@
     /*
      * maps memory from ashmem, with the given name for debugging
      */
-    MemoryHeapBase(size_t size, uint32_t flags = 0, char const* name = NULL);
+    MemoryHeapBase(size_t size, uint32_t flags = 0, char const* name = nullptr);
 
     virtual ~MemoryHeapBase();
 
@@ -74,7 +74,7 @@
     /* this is only needed as a workaround, use only if you know
      * what you are doing */
     status_t setDevice(const char* device) {
-        if (mDevice == 0)
+        if (mDevice == nullptr)
             mDevice = device;
         return mDevice ? NO_ERROR : ALREADY_EXISTS;
     }
@@ -83,7 +83,7 @@
             MemoryHeapBase();
     // init() takes ownership of fd
     status_t init(int fd, void *base, int size,
-            int flags = 0, const char* device = NULL);
+            int flags = 0, const char* device = nullptr);
 
 private:
     status_t mapfd(int fd, size_t size, uint32_t offset = 0);
diff --git a/libs/binder/include/binder/Parcel.h b/libs/binder/include/binder/Parcel.h
index b9a3ae6..14478b5 100644
--- a/libs/binder/include/binder/Parcel.h
+++ b/libs/binder/include/binder/Parcel.h
@@ -91,7 +91,7 @@
     // IPCThreadState, which as an optimization may optionally be
     // passed in.
     bool                enforceInterface(const String16& interface,
-                                         IPCThreadState* threadState = NULL) const;
+                                         IPCThreadState* threadState = nullptr) const;
     bool                checkInterface(IBinder*) const;
 
     void                freeData();
@@ -552,7 +552,7 @@
         friend class Parcel;
     public:
         inline const void* data() const { return mData; }
-        inline void* mutableData() { return isMutable() ? mData : NULL; }
+        inline void* mutableData() { return isMutable() ? mData : nullptr; }
     };
 
     class WritableBlob : public Blob {
@@ -592,7 +592,7 @@
     }
     if (size) {
         void* buffer = writeInplace(size);
-        if (buffer == NULL)
+        if (buffer == nullptr)
             return NO_MEMORY;
         return val.flatten(buffer, size);
     }
@@ -620,7 +620,7 @@
     }
     if (size) {
         void const* buffer = readInplace(size);
-        return buffer == NULL ? NO_MEMORY :
+        return buffer == nullptr ? NO_MEMORY :
                 val.unflatten(buffer, size);
     }
     return NO_ERROR;
diff --git a/libs/binder/tests/binderLibTest.cpp b/libs/binder/tests/binderLibTest.cpp
index f23ac52..73c2eba 100644
--- a/libs/binder/tests/binderLibTest.cpp
+++ b/libs/binder/tests/binderLibTest.cpp
@@ -1189,7 +1189,7 @@
                     return ret;
                 }
                 buf = data.readInplace(size);
-                if (buf == NULL) {
+                if (buf == nullptr) {
                     return BAD_VALUE;
                 }
                 ret = write(fd.get(), buf, size);
diff --git a/libs/nativewindow/include/android/hardware_buffer.h b/libs/nativewindow/include/android/hardware_buffer.h
index 277560b..5c1b510 100644
--- a/libs/nativewindow/include/android/hardware_buffer.h
+++ b/libs/nativewindow/include/android/hardware_buffer.h
@@ -154,6 +154,8 @@
 
 typedef struct AHardwareBuffer AHardwareBuffer;
 
+#if __ANDROID_API__ >= 26
+
 /**
  * Allocates a buffer that backs an AHardwareBuffer using the passed
  * AHardwareBuffer_Desc.
@@ -246,6 +248,8 @@
  */
 int AHardwareBuffer_recvHandleFromUnixSocket(int socketFd, AHardwareBuffer** outBuffer) __INTRODUCED_IN(26);
 
+#endif // __ANDROID_API__ >= 26
+
 __END_DECLS
 
 #endif // ANDROID_HARDWARE_BUFFER_H
diff --git a/libs/nativewindow/include/android/native_window.h b/libs/nativewindow/include/android/native_window.h
index fd5d8b5..ba5295b 100644
--- a/libs/nativewindow/include/android/native_window.h
+++ b/libs/nativewindow/include/android/native_window.h
@@ -108,33 +108,33 @@
  * Acquire a reference on the given {@link ANativeWindow} object. This prevents the object
  * from being deleted until the reference is removed.
  */
-void ANativeWindow_acquire(ANativeWindow* window) __INTRODUCED_IN(26);
+void ANativeWindow_acquire(ANativeWindow* window);
 
 /**
  * Remove a reference that was previously acquired with {@link ANativeWindow_acquire()}.
  */
-void ANativeWindow_release(ANativeWindow* window) __INTRODUCED_IN(26);
+void ANativeWindow_release(ANativeWindow* window);
 
 /**
  * Return the current width in pixels of the window surface.
  *
  * \return negative value on error.
  */
-int32_t ANativeWindow_getWidth(ANativeWindow* window) __INTRODUCED_IN(26);
+int32_t ANativeWindow_getWidth(ANativeWindow* window);
 
 /**
  * Return the current height in pixels of the window surface.
  *
  * \return a negative value on error.
  */
-int32_t ANativeWindow_getHeight(ANativeWindow* window) __INTRODUCED_IN(26);
+int32_t ANativeWindow_getHeight(ANativeWindow* window);
 
 /**
  * Return the current pixel format (AHARDWAREBUFFER_FORMAT_*) of the window surface.
  *
  * \return a negative value on error.
  */
-int32_t ANativeWindow_getFormat(ANativeWindow* window) __INTRODUCED_IN(26);
+int32_t ANativeWindow_getFormat(ANativeWindow* window);
 
 /**
  * Change the format and size of the window buffers.
@@ -154,7 +154,7 @@
  * \return 0 for success, or a negative value on error.
  */
 int32_t ANativeWindow_setBuffersGeometry(ANativeWindow* window,
-        int32_t width, int32_t height, int32_t format) __INTRODUCED_IN(26);
+        int32_t width, int32_t height, int32_t format);
 
 /**
  * Lock the window's next drawing surface for writing.
@@ -167,7 +167,7 @@
  * \return 0 for success, or a negative value on error.
  */
 int32_t ANativeWindow_lock(ANativeWindow* window, ANativeWindow_Buffer* outBuffer,
-        ARect* inOutDirtyBounds) __INTRODUCED_IN(26);
+        ARect* inOutDirtyBounds);
 
 /**
  * Unlock the window's drawing surface after previously locking it,
@@ -175,7 +175,9 @@
  *
  * \return 0 for success, or a negative value on error.
  */
-int32_t ANativeWindow_unlockAndPost(ANativeWindow* window) __INTRODUCED_IN(26);
+int32_t ANativeWindow_unlockAndPost(ANativeWindow* window);
+
+#if __ANDROID_API__ >= 26
 
 /**
  * Set a transform that will be applied to future buffers posted to the window.
@@ -185,6 +187,8 @@
  */
 int32_t ANativeWindow_setBuffersTransform(ANativeWindow* window, int32_t transform) __INTRODUCED_IN(26);
 
+#endif // __ANDROID_API__ >= 26
+
 #ifdef __cplusplus
 };
 #endif
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 19a46f6..98c84af 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -13,6 +13,7 @@
         "-Wno-unused-parameter",
     ],
     shared_libs: [
+        "libbase",
         "libcutils",
         "liblog",
         "libutils",