Timeline: add support for deferred canvas rasterization

Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp

Index: Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
diff --git a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
index 0c25d1d773f4465d4a9523222349b8654fd471a5..604395add6c7a7dd045b3cb7b886339163e002f3 100644
--- a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
+++ b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.cpp
@@ -30,6 +30,7 @@
 #include "GrContext.h"
 #include "SkDevice.h"
 #include "SkSurface.h"
+#include "core/platform/PlatformInstrumentation.h"
 #include "core/platform/chromium/TraceEvent.h"
 #include "core/platform/graphics/GraphicsContext3D.h"
 #include "core/platform/graphics/GraphicsLayer.h"
@@ -193,6 +194,7 @@ bool Canvas2DLayerBridge::prepareMailbox(WebKit::WebExternalTextureMailbox* outM
     // Early exit if canvas was not drawn to since last prepareMailbox
     if (image->uniqueID() == m_lastImageId)
         return false;
+    PlatformInstrumentation::willRasterizeCanvas();
     m_lastImageId = image->uniqueID();
 
     mailboxInfo = createMailboxInfo();
@@ -223,6 +225,7 @@ bool Canvas2DLayerBridge::prepareMailbox(WebKit::WebExternalTextureMailbox* outM
     m_context->bindTexture(GraphicsContext3D::TEXTURE_2D, savedTexBinding);
 
     *outMailbox = mailboxInfo->m_mailbox;
+    PlatformInstrumentation::didRasterizeCanvas();
     return true;
 #else
     ASSERT_NOT_REACHED();