Add UMA metrics to OffscreenCanvas's commit type

third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp

Index: third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
index 32204cf95bc0171c5e8dd8cb31b6f30b823703c3..d1a6788683b9f14cc147e7f022fe7d9661fd5c23 100644
--- a/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
+++ b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
@@ -12,9 +12,8 @@
 #include "cc/quads/texture_draw_quad.h"
 #include "cc/resources/returned_resource.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
-#include "platform/RuntimeEnabledFeatures.h"
+#include "platform/Histogram.h"
 #include "platform/graphics/gpu/SharedGpuContext.h"
-#include "platform/RuntimeEnabledFeatures.h"
 #include "public/platform/InterfaceProvider.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebGraphicsContext3DProvider.h"
@@ -188,18 +187,27 @@ void OffscreenCanvasFrameDispatcherImpl::dispatchFrame(
   // TODO(crbug.com/646022): making this overlay-able.
   resource.is_overlay_candidate = false;
 
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(
+      EnumerationHistogram, commitTypeHistogram,
+      new EnumerationHistogram("OffscreenCanvas.CommitType",
+                               OffscreenCanvasCommitTypeCount));
   if (!image->isTextureBacked() &&
-      !Platform::current()->isGPUCompositingEnabled())
+      !Platform::current()->isGPUCompositingEnabled()) {
+    commitTypeHistogram.count(CommitSoftwareCanvasSoftwareCompositing);
     setTransferableResourceInMemory(resource, image);
-  else if (!image->isTextureBacked() &&
-           Platform::current()->isGPUCompositingEnabled())
+  } else if (!image->isTextureBacked() &&
+             Platform::current()->isGPUCompositingEnabled()) {
+    commitTypeHistogram.count(CommitSoftwareCanvasGPUCompositing);
     setTransferableResourceMemoryToTexture(resource, image);
-  else if (image->isTextureBacked() &&
-           (!Platform::current()->isGPUCompositingEnabled() ||
-            isWebGLSoftwareRendering))
+  } else if (image->isTextureBacked() &&
+             (!Platform::current()->isGPUCompositingEnabled() ||
+              isWebGLSoftwareRendering)) {
+    commitTypeHistogram.count(CommitGPUCanvasSoftwareCompositing);
     setTransferableResourceInMemory(resource, image);
-  else
+  } else {
+    commitTypeHistogram.count(CommitGPUCanvasGPUCompositing);
     setTransferableResourceInTexture(resource, image);
+  }
 
   m_nextResourceId++;
   frame.delegated_frame_data->resource_list.push_back(std::move(resource));