DevTools: add instrumentation for deferred canvas rasterization

Source/core/platform/PlatformInstrumentation.h

Index: Source/core/platform/PlatformInstrumentation.h
diff --git a/Source/core/platform/PlatformInstrumentation.h b/Source/core/platform/PlatformInstrumentation.h
index 5c449930b19e3eee165fbd14b65430828f46b923..ec8bd8ab6758eea07b0e858ff42c76fedc8b8d1a 100644
--- a/Source/core/platform/PlatformInstrumentation.h
+++ b/Source/core/platform/PlatformInstrumentation.h
@@ -52,6 +52,7 @@ class PlatformInstrumentation {
 public:
     static const char ImageDecodeEvent[];
     static const char ImageResizeEvent[];
+    static const char RasterizeCanvasEvent[];
 
     static const char ImageTypeArgument[];
     static const char CachedArgument[];
@@ -64,6 +65,9 @@ public:
     static void willResizeImage(bool shouldCache);
     static void didResizeImage();
 
+    static void willRasterizeCanvas();
+    static void didRasterizeCanvas();
+
 private:
     static const char CategoryName[];
 
@@ -100,6 +104,16 @@ inline void PlatformInstrumentation::didResizeImage()
     m_client->didResizeImage();
 }
 
+inline void PlatformInstrumentation::willRasterizeCanvas()
+{
+    TRACE_EVENT_BEGIN0(CategoryName, RasterizeCanvasEvent);
+}
+
+inline void PlatformInstrumentation::didRasterizeCanvas()
+{
+    TRACE_EVENT_END0(CategoryName, RasterizeCanvasEvent);
+}
+
 } // namespace WebCore
 
 #endif // PlatformInstrumentation_h