WIP GPU scheduler + delayed activation / tile draw

cc/raster/bitmap_raster_buffer_provider.h

Index: cc/raster/bitmap_raster_buffer_provider.h
diff --git a/cc/raster/bitmap_raster_buffer_provider.h b/cc/raster/bitmap_raster_buffer_provider.h
index ded16f5f76af1238277c58523e3830659778fcc3..1b91ad9f84a221bc25665dfbe88280fc933542f3 100644
--- a/cc/raster/bitmap_raster_buffer_provider.h
+++ b/cc/raster/bitmap_raster_buffer_provider.h
@@ -34,6 +34,9 @@ class CC_EXPORT BitmapRasterBufferProvider : public RasterBufferProvider {
       uint64_t previous_content_id) override;
   void ReleaseBufferForRaster(std::unique_ptr<RasterBuffer> buffer) override;
   void OrderingBarrier() override;
+  bool IsResourceReadyToDraw(const Resource* resource) override;
+  void SignalResourcesReadyToDraw(const std::vector<const Resource*>& resources,
+                                  const base::Closure& callback) override;
   ResourceFormat GetResourceFormat(bool must_support_alpha) const override;
   bool IsResourceSwizzleRequired(bool must_support_alpha) const override;
   bool CanPartialRasterIntoProvidedResource() const override;