Add logic to ResourceProvider to correctly lock GpuMemoryBuffer Resources.

cc/output/gl_renderer.h

Index: cc/output/gl_renderer.h
diff --git a/cc/output/gl_renderer.h b/cc/output/gl_renderer.h
index d1de2c24595fcd0835db3f00cf27aa592c08d331..2ef63a999ef9af25eb1dd7cecfe302a307e6801f 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -258,10 +258,19 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
   void ScheduleCALayers(DrawingFrame* frame);
   void ScheduleOverlays(DrawingFrame* frame);
 
-  using OverlayResourceLockList =
-      std::vector<std::unique_ptr<ResourceProvider::ScopedReadLockGL>>;
+  using OverlayResourceLock =
+      std::unique_ptr<ResourceProvider::ScopedReadLockGpuMemoryBuffer>;
+  using OverlayResourceLockList = std::vector<OverlayResourceLock>;
+
+  // Resources that have been sent to the GPU process, but not yet swapped.
   OverlayResourceLockList pending_overlay_resources_;
-  std::deque<OverlayResourceLockList> swapped_overlay_resources_;
+
+  // Resources that should be shortly swapped by the GPU process.
+  std::deque<OverlayResourceLockList> swapping_overlay_resources_;
+
+  // Resources that the GPU process has finished swapping.
+  std::map<ResourceId, OverlayResourceLock>
+      swapped_and_acked_overlay_resources_;
 
   RendererCapabilitiesImpl capabilities_;