[devmgr] Fix ENABLE_DRIVER_TRACING=true build

Tested: build with ENABLE_DRIVER_TRACING=true, boot result
Change-Id: If5cb8ce816c787cdc77fbec1dc21ee1949081a10
diff --git a/system/core/devmgr/devhost/tracing.cpp b/system/core/devmgr/devhost/tracing.cpp
index 4032995..9b0170b 100644
--- a/system/core/devmgr/devhost/tracing.cpp
+++ b/system/core/devmgr/devhost/tracing.cpp
@@ -9,6 +9,8 @@
 
 #include "../shared/log.h"
 
+namespace devmgr {
+
 zx_status_t devhost_start_trace_provider() {
     async_loop_t* loop;
     zx_status_t status = async_loop_create(&kAsyncLoopConfigNoAttachToThread, &loop);
@@ -37,3 +39,5 @@
     log(INFO, "devhost: trace provider registry begun\n");
     return ZX_OK;
 }
+
+} // namespace devmgr
diff --git a/system/core/devmgr/devhost/tracing.h b/system/core/devmgr/devhost/tracing.h
index 81b2100..4ecda69 100644
--- a/system/core/devmgr/devhost/tracing.h
+++ b/system/core/devmgr/devhost/tracing.h
@@ -6,7 +6,11 @@
 
 #include <zircon/types.h>
 
+namespace devmgr {
+
 // Register the devhost as a "trace provider" with the trace manager.
 // There is no corresponding "unregister" function: we remain registered
 // until either us or the manager terminate.
 zx_status_t devhost_start_trace_provider();
+
+} // namespace devmgr
diff --git a/system/core/devmgr/shared/log.h b/system/core/devmgr/shared/log.h
index f4f00c9..11f4e2e 100644
--- a/system/core/devmgr/shared/log.h
+++ b/system/core/devmgr/shared/log.h
@@ -23,6 +23,6 @@
 
 extern uint32_t log_flags;
 
-#define log(flag, fmt...) do { if (LOG_##flag & log_flags) printf(fmt); } while (0)
+#define log(flag, fmt...) do { if (LOG_##flag & ::devmgr::log_flags) printf(fmt); } while (0)
 
 } // namespace devmgr