cc: Do bitmap conversion for RasterBuffer in the worker thread.

cc/resources/resource_provider_unittest.cc

Index: cc/resources/resource_provider_unittest.cc
diff --git a/cc/resources/resource_provider_unittest.cc b/cc/resources/resource_provider_unittest.cc
index 4782bd57a30558b4f4cd322174e568d3f560eb18..deea4b540a14ca32b0366dea852ea160c77ff4ef 100644
--- a/cc/resources/resource_provider_unittest.cc
+++ b/cc/resources/resource_provider_unittest.cc
@@ -954,9 +954,10 @@ TEST_P(ResourceProviderTest, TransferSoftwareResources) {
   SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());
   RasterBuffer* raster_buffer =
       child_resource_provider_->AcquireImageRasterBuffer(id3);
-  SkCanvas* canvas = raster_buffer->AcquireSkCanvas();
+  skia::RefPtr<SkCanvas> canvas = raster_buffer->AcquireSkCanvas();
   canvas->writePixels(info, data3, info.minRowBytes(), 0, 0);
-  raster_buffer->ReleaseSkCanvas();
+  raster_buffer->ReleaseSkCanvas(canvas.get());
+  canvas.clear();
   child_resource_provider_->ReleaseImageRasterBuffer(id3);
 
   scoped_ptr<base::SharedMemory> shared_memory(new base::SharedMemory());
@@ -2940,12 +2941,11 @@ TEST_P(ResourceProviderTest, PixelBufferLostContext) {
   context->loseContextCHROMIUM(GL_GUILTY_CONTEXT_RESET_ARB,
                                GL_INNOCENT_CONTEXT_RESET_ARB);
 
-  resource_provider->AcquirePixelRasterBuffer(id);
-  RasterBuffer* raster_buffer = resource_provider->MapPixelRasterBuffer(id);
-  SkCanvas* canvas = raster_buffer->AcquireSkCanvas();
-  EXPECT_TRUE(canvas == NULL);
-  raster_buffer->ReleaseSkCanvas();
-  resource_provider->UnmapPixelRasterBuffer(id);
+  RasterBuffer* raster_buffer = resource_provider->AcquirePixelRasterBuffer(id);
+  skia::RefPtr<SkCanvas> canvas = raster_buffer->AcquireSkCanvas();
+  EXPECT_TRUE(canvas.get() == NULL);
+  raster_buffer->ReleaseSkCanvas(canvas.get());
+  canvas.clear();
   resource_provider->ReleasePixelRasterBuffer(id);
   Mock::VerifyAndClearExpectations(context);
 }
@@ -3075,10 +3075,11 @@ TEST_P(ResourceProviderTest, Image_Bitmap) {
   bitmap.allocN32Pixels(size.width(), size.height());
   *(bitmap.getAddr32(0, 0)) = kBadBeef;
   RasterBuffer* raster_buffer = resource_provider->AcquireImageRasterBuffer(id);
-  SkCanvas* canvas = raster_buffer->AcquireSkCanvas();
+  skia::RefPtr<SkCanvas> canvas = raster_buffer->AcquireSkCanvas();
   ASSERT_TRUE(!!canvas);
   canvas->writePixels(bitmap, 0, 0);
-  raster_buffer->ReleaseSkCanvas();
+  raster_buffer->ReleaseSkCanvas(canvas.get());
+  canvas.clear();
   resource_provider->ReleaseImageRasterBuffer(id);
 
   {
@@ -3204,10 +3205,11 @@ TEST_P(ResourceProviderTest, CopyResource_Bitmap) {
   *(bitmap.getAddr32(0, 0)) = kBadBeef;
   RasterBuffer* raster_buffer =
       resource_provider->AcquireImageRasterBuffer(source_id);
-  SkCanvas* canvas = raster_buffer->AcquireSkCanvas();
+  skia::RefPtr<SkCanvas> canvas = raster_buffer->AcquireSkCanvas();
   ASSERT_TRUE(!!canvas);
   canvas->writePixels(bitmap, 0, 0);
-  raster_buffer->ReleaseSkCanvas();
+  raster_buffer->ReleaseSkCanvas(canvas.get());
+  canvas.clear();
   resource_provider->ReleaseImageRasterBuffer(source_id);
 
   dest_id = resource_provider->CreateResource(