Delay activation/draw on GPU tile work completion

cc/raster/gpu_raster_buffer_provider.cc

Index: cc/raster/gpu_raster_buffer_provider.cc
diff --git a/cc/raster/gpu_raster_buffer_provider.cc b/cc/raster/gpu_raster_buffer_provider.cc
index 3a90041237dbb03a32a2d19f6e4fb8b9afcb7889..55253e94f1a020eec2d8956c4fff0d027b0474af 100644
--- a/cc/raster/gpu_raster_buffer_provider.cc
+++ b/cc/raster/gpu_raster_buffer_provider.cc
@@ -17,6 +17,7 @@
 #include "cc/playback/raster_source.h"
 #include "cc/raster/scoped_gpu_raster.h"
 #include "cc/resources/resource.h"
+#include "gpu/command_buffer/client/context_support.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "third_party/skia/include/core/SkMultiPictureDraw.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
@@ -234,6 +235,26 @@ bool GpuRasterBufferProvider::CanPartialRasterIntoProvidedResource() const {
   return msaa_sample_count_ == 0;
 }
 
+uint64_t GpuRasterBufferProvider::SetReadyToDrawCallback(
+    const ResourceProvider::ResourceIdArray& resource_ids,
+    const base::Callback<void(uint64_t)>& callback,
+    uint64_t pending_callback_id) const {
+  if (!async_worker_context_enabled_)
+    return 0;
+
+  gpu::SyncToken sync_token =
+      resource_provider_->GetSyncTokenForResources(resource_ids);
+  uint64_t callback_id = sync_token.release_count();
+  DCHECK_NE(callback_id, 0u);
+
+  if (callback_id != pending_callback_id) {
+    compositor_context_provider_->ContextSupport()->SignalSyncToken(
+        sync_token, base::Bind(callback, callback_id));
+  }
+
+  return callback_id;
+}
+
 void GpuRasterBufferProvider::Shutdown() {
   pending_raster_buffers_.clear();
 }