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 97fb5812f5f986e4a4dd573b87f21230ddbd5333..d87492844d4e7812079143f3cfbcab8c4f46a602 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"
@@ -186,6 +187,47 @@ bool GpuRasterBufferProvider::CanPartialRasterIntoProvidedResource() const {
   return msaa_sample_count_ == 0;
 }
 
+bool GpuRasterBufferProvider::IsResourceReadyToDraw(
+    ResourceId resource_id) const {
+  if (!async_worker_context_enabled_)
+    return true;
+
+  ResourceProvider::ResourceIdArray resources;
+  resources.push_back(resource_id);
+  gpu::SyncToken sync_token =
+      resource_provider_->GetSyncTokenForResources(resources);

[vmpstr, 2017/01/30 19:51:19]

nit: this can just be 

resource_provider_->GetSyncTokenForResources({resource_id});

(I think that's allowed?)

+  if (!sync_token.HasData())
+    return true;
+
+  // IsSyncTokenSignalled is threadsafe, no need for worker context lock.
+  return worker_context_provider_->ContextSupport()->IsSyncTokenSignalled(
+      sync_token);
+}
+
+uint64_t GpuRasterBufferProvider::SetReadyToDrawCallback(
+    const ResourceProvider::ResourceIdArray& resource_ids,
+    const base::Closure& 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 the callback is different from the one the caller is already waiting on,
+  // pass the callback through to SignalSinkToken. Otherwise the request is
+  // redundant.
+  if (callback_id != pending_callback_id) {
+    // SignalSyncToken is threadsafe, no need for worker context lock.
+    worker_context_provider_->ContextSupport()->SignalSyncToken(sync_token,
+                                                                callback);
+  }
+
+  return callback_id;
+}
+
 void GpuRasterBufferProvider::Shutdown() {
   pending_raster_buffers_.clear();
 }