Expose scroll by pixel

In support of https://fuchsia.atlassian.net/browse/WEB-3.

Change-Id: I14bc8a14c09b5c28345a0b75bcc1fada2eb812f1
diff --git a/Source/WebKit/fuchsia/WebView.cpp b/Source/WebKit/fuchsia/WebView.cpp
index 4266059..355a993 100644
--- a/Source/WebKit/fuchsia/WebView.cpp
+++ b/Source/WebKit/fuchsia/WebView.cpp
@@ -224,6 +224,15 @@
     scrollInternal(ScrollDirection::ScrollRight, ScrollGranularity::ScrollByLine);
 }
 
+void WebView::scrollPixels(int deltaX, int deltaY)
+{
+    Frame* frame = m_frameLoaderClient->frame();
+    if (frame) {
+        FrameView* view = frame->view();
+        view->scrollBy(IntSize(deltaX, deltaY));
+    }
+}
+
 void WebView::scrollInternal(uint8_t direction, uint8_t granularity)
 {
     if (m_page) {
diff --git a/Source/WebKit/fuchsia/WebView.h b/Source/WebKit/fuchsia/WebView.h
index f5363df..d499af0 100644
--- a/Source/WebKit/fuchsia/WebView.h
+++ b/Source/WebKit/fuchsia/WebView.h
@@ -65,6 +65,7 @@
     void scrollUpOneLine();
     void scrollLeftOneLine();
     void scrollRightOneLine();
+    void scrollPixels(int deltaX, int deltaY);
 
     void layoutAndPaint();