Delay activation/draw on GPU tile work completion

cc/raster/raster_buffer_provider.h

Index: cc/raster/raster_buffer_provider.h
diff --git a/cc/raster/raster_buffer_provider.h b/cc/raster/raster_buffer_provider.h
index 8c3b64473673c34ca7b73f0238cc8fd3462e58de..701fec97f72063c1a458c341da75a0e81e9991d5 100644
--- a/cc/raster/raster_buffer_provider.h
+++ b/cc/raster/raster_buffer_provider.h
@@ -12,6 +12,7 @@
 #include "cc/raster/task_graph_runner.h"
 #include "cc/raster/tile_task.h"
 #include "cc/resources/resource_format.h"
+#include "cc/resources/resource_provider.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
@@ -63,6 +64,19 @@ class CC_EXPORT RasterBufferProvider {
   // the Resource provided in AcquireBufferForRaster.
   virtual bool CanPartialRasterIntoProvidedResource() const = 0;
 
+  // Returns true if the indicated resource is ready to draw.
+  virtual bool IsResourceReadyToDraw(ResourceId id) const = 0;
+
+  // Calls the provided |callback| when the provided |resources| are ready to
+  // draw. Returns a callback ID which can be used to track this callback.
+  // Will return 0 if no callback is needed (resources are already ready to
+  // draw). The caller may optionally pass the ID of a pending callback to
+  // avoid creating a new callback unnecessarily.
+  virtual uint64_t SetReadyToDrawCallback(
+      const ResourceProvider::ResourceIdArray& resource_ids,
+      const base::Callback<void()>& callback,
+      uint64_t pending_callback_id) const = 0;
+
   // Shutdown for doing cleanup.
   virtual void Shutdown() = 0;