Expose locks for CopyFromCompositingSurface/CopyFromBackingStore API

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 8529331bf3101307bfabfdfd606f9e5156d3f35e..71e241d9b8404f5429058d9beed338729de745c2 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -748,6 +748,16 @@ void RenderWidgetHostImpl::CopyFromBackingStore(
   callback.Run(result, output.GetBitmap());
 }
 
+void RenderWidgetHostImpl::LockForCopyFromBackingStore() {
+  if (view_)
+    view_->LockSurfaceForCopy();
+}
+
+void RenderWidgetHostImpl::UnlockForCopyFromBackingStore() {
+  if (view_)
+    view_->UnlockSurfaceForCopy();
+}
+
 #if defined(TOOLKIT_GTK)
 bool RenderWidgetHostImpl::CopyFromBackingStoreToGtkWindow(
     const gfx::Rect& dest_rect, GdkWindow* target) {