Add UMA metrics to OffscreenCanvas's commit type

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef OffscreenCanvasFrameDispatcherImpl_h
 #define OffscreenCanvasFrameDispatcherImpl_h
 
 #include "cc/ipc/mojo_compositor_frame_sink.mojom-blink.h"
 #include "cc/resources/shared_bitmap.h"
 #include "cc/surfaces/surface_id.h"
@@ skipping 19 matching lines @@
 
   // OffscreenCanvasFrameDispatcher implementation.
   ~OffscreenCanvasFrameDispatcherImpl() override {}
   void dispatchFrame(RefPtr<StaticBitmapImage>,
                      bool isWebGLSoftwareRendering = false) override;
 
   // cc::mojom::blink::MojoCompositorFrameSinkClient implementation.
   void ReturnResources(
       Vector<cc::mojom::blink::ReturnedResourcePtr> resources) override;
 
+  enum OffscreenCanvasCommitType {

[Ilya Sherman, 2016/10/11 00:54:11]

Please document that this enum is used to back an UMA histogram, and should
therefore be treated as append-only.

[xidachen, 2016/10/11 17:21:16]

Done.

+    CommitGPUCanvasGPUCompositing = 0,
+    CommitGPUCanvasSoftwareCompositing = 1,
+    CommitSoftwareCanvasGPUCompositing = 2,
+    CommitSoftwareCanvasSoftwareCompositing = 3,
+    OffscreenCanvasCommitTypeCount,
+  };
+
  private:
   const cc::SurfaceId m_surfaceId;
   const int m_width;
   const int m_height;
 
   unsigned m_nextResourceId;
   HashMap<unsigned, RefPtr<StaticBitmapImage>> m_cachedImages;
   HashMap<unsigned, std::unique_ptr<cc::SharedBitmap>> m_sharedBitmaps;
   HashMap<unsigned, GLuint> m_cachedTextureIds;
 
   bool verifyImageSize(const sk_sp<SkImage>&);
 
   cc::mojom::blink::MojoCompositorFrameSinkPtr m_sink;
   mojo::Binding<cc::mojom::blink::MojoCompositorFrameSinkClient> m_binding;
 
   void setTransferableResourceInMemory(cc::TransferableResource&,
                                        RefPtr<StaticBitmapImage>);
   void setTransferableResourceMemoryToTexture(cc::TransferableResource&,
                                               RefPtr<StaticBitmapImage>);
   void setTransferableResourceInTexture(cc::TransferableResource&,
                                         RefPtr<StaticBitmapImage>);
 };
 
 }  // namespace blink
 
 #endif  // OffscreenCanvasFrameDispatcherImpl_h