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

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index ff0652465d9047447fb376bd097988db9828acdb..901c49a07261b03222b2b9d60b041837a009555a 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -401,7 +401,6 @@ ResourceProvider::RasterBuffer::RasterBuffer(
     ResourceProvider* resource_provider)
     : resource_(resource),
       resource_provider_(resource_provider),
-      locked_canvas_(NULL),
       canvas_save_count_(0) {
   DCHECK(resource_);
   DCHECK(resource_provider_);
@@ -409,7 +408,7 @@ ResourceProvider::RasterBuffer::RasterBuffer(
 
 ResourceProvider::RasterBuffer::~RasterBuffer() {}
 
-SkCanvas* ResourceProvider::RasterBuffer::LockForWrite() {
+void ResourceProvider::RasterBuffer::LockForWrite() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
                "ResourceProvider::RasterBuffer::LockForWrite");
 
@@ -417,7 +416,6 @@ SkCanvas* ResourceProvider::RasterBuffer::LockForWrite() {
 
   locked_canvas_ = DoLockForWrite();
   canvas_save_count_ = locked_canvas_ ? locked_canvas_->save() : 0;
-  return locked_canvas_;
 }
 
 bool ResourceProvider::RasterBuffer::UnlockForWrite() {
@@ -527,21 +525,27 @@ SkCanvas* ResourceProvider::BitmapRasterBuffer::DoLockForWrite() {
   return raster_canvas_.get();
 }
 
-bool ResourceProvider::BitmapRasterBuffer::DoUnlockForWrite() {
-  raster_canvas_.clear();
+void ResourceProvider::BitmapRasterBuffer::Flush() {
+  // Note that this function is called from a worker thread.
 
   // getGenerationID returns a non-zero, unique value corresponding to the
   // pixels in bitmap. Hence, a change since DoLockForWrite was called means the
   // bitmap has changed.
   bool raster_bitmap_changed =
       raster_bitmap_generation_id_ != raster_bitmap_.getGenerationID();
-
   if (raster_bitmap_changed) {
     SkColorType buffer_colorType =
         ResourceFormatToSkColorType(resource()->format);
     if (mapped_buffer_ && (buffer_colorType != raster_bitmap_.colorType()))
       CopyBitmap(raster_bitmap_, mapped_buffer_, buffer_colorType);
   }
+}
+
+bool ResourceProvider::BitmapRasterBuffer::DoUnlockForWrite() {
+  raster_canvas_.clear();
+
+  bool raster_bitmap_changed =
+      raster_bitmap_generation_id_ != raster_bitmap_.getGenerationID();
   raster_bitmap_.reset();
 
   UnmapBuffer();
@@ -1727,7 +1731,7 @@ void ResourceProvider::DeleteAndReturnUnusedResourcesToChild(
   }
 }
 
-SkCanvas* ResourceProvider::MapGpuRasterBuffer(ResourceId id) {
+RasterCanvas* ResourceProvider::MapGpuRasterBuffer(ResourceId id) {
   // Resource needs to be locked for write since GpuRasterBuffer writes
   // directly to it.
   LockForWrite(id);
@@ -1736,7 +1740,8 @@ SkCanvas* ResourceProvider::MapGpuRasterBuffer(ResourceId id) {
     resource->gpu_raster_buffer.reset(
         new GpuRasterBuffer(resource, this, use_distance_field_text_));
   }
-  return resource->gpu_raster_buffer->LockForWrite();
+  resource->gpu_raster_buffer->LockForWrite();
+  return resource->gpu_raster_buffer.get();
 }
 
 void ResourceProvider::UnmapGpuRasterBuffer(ResourceId id) {
@@ -1746,12 +1751,13 @@ void ResourceProvider::UnmapGpuRasterBuffer(ResourceId id) {
   UnlockForWrite(id);
 }
 
-SkCanvas* ResourceProvider::MapImageRasterBuffer(ResourceId id) {
+RasterCanvas* ResourceProvider::MapImageRasterBuffer(ResourceId id) {
   Resource* resource = GetResource(id);
   AcquireImage(resource);
   if (!resource->image_raster_buffer.get())
     resource->image_raster_buffer.reset(new ImageRasterBuffer(resource, this));
-  return resource->image_raster_buffer->LockForWrite();
+  resource->image_raster_buffer->LockForWrite();
+  return resource->image_raster_buffer.get();
 }
 
 bool ResourceProvider::UnmapImageRasterBuffer(ResourceId id) {
@@ -1772,10 +1778,11 @@ void ResourceProvider::ReleasePixelRasterBuffer(ResourceId id) {
   ReleasePixelBuffer(resource);
 }
 
-SkCanvas* ResourceProvider::MapPixelRasterBuffer(ResourceId id) {
+RasterCanvas* ResourceProvider::MapPixelRasterBuffer(ResourceId id) {
   Resource* resource = GetResource(id);
   DCHECK(resource->pixel_raster_buffer.get());
-  return resource->pixel_raster_buffer->LockForWrite();
+  resource->pixel_raster_buffer->LockForWrite();
+  return resource->pixel_raster_buffer.get();
 }
 
 bool ResourceProvider::UnmapPixelRasterBuffer(ResourceId id) {