cc: Add ScopedWriteLock classes for raster to GpuMemoryBuffer or using Ganesh.

cc/resources/pixel_buffer_raster_worker_pool.cc

Index: cc/resources/pixel_buffer_raster_worker_pool.cc
diff --git a/cc/resources/pixel_buffer_raster_worker_pool.cc b/cc/resources/pixel_buffer_raster_worker_pool.cc
index 87c4a791fb4401750e0f9c42f47ca3ceb887d7bf..693f643a8015df693a6d95a97d137a8e8695469e 100644
--- a/cc/resources/pixel_buffer_raster_worker_pool.cc
+++ b/cc/resources/pixel_buffer_raster_worker_pool.cc
@@ -449,11 +449,6 @@ void PixelBufferRasterWorkerPool::CheckForCompletedUploads() {
     task->CompleteOnOriginThread(this);
     task->DidComplete();
 
-    // Async set pixels commands are not necessarily processed in-sequence with
-    // drawing commands. Read lock fences are required to ensure that async
-    // commands don't access the resource while used for drawing.
-    resource_provider_->EnableReadLockFences(task->resource()->id());
-
     DCHECK(std::find(completed_raster_tasks_.begin(),
                      completed_raster_tasks_.end(),
                      task) == completed_raster_tasks_.end());