Stop disabling force_compositing_mode for background RenderViews.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index c547aad70b0a0880126a0c15ad9374156f551cde..190320a48677a9de9f98a9a0ecb45e44cdc2785f 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -348,7 +348,8 @@ void RenderWidget::ScreenMetricsEmulator::OnShowContextMenu(
 RenderWidget::RenderWidget(blink::WebPopupType popup_type,
                            const blink::WebScreenInfo& screen_info,
                            bool swapped_out,
-                           bool hidden)
+                           bool hidden,
+                           bool never_visible)
     : routing_id_(MSG_ROUTING_NONE),
       surface_id_(0),
       webwidget_(NULL),
@@ -365,6 +366,7 @@ RenderWidget::RenderWidget(blink::WebPopupType popup_type,
       num_swapbuffers_complete_pending_(0),
       did_show_(false),
       is_hidden_(hidden),
+      never_visible_(never_visible),
       is_fullscreen_(false),
       needs_repainting_on_restore_(false),
       has_focus_(false),
@@ -433,7 +435,7 @@ RenderWidget* RenderWidget::Create(int32 opener_id,
                                    const blink::WebScreenInfo& screen_info) {
   DCHECK(opener_id != MSG_ROUTING_NONE);
   scoped_refptr<RenderWidget> widget(
-      new RenderWidget(popup_type, screen_info, false, false));
+      new RenderWidget(popup_type, screen_info, false, false, false));
   if (widget->Init(opener_id)) {  // adds reference on success.
     return widget.get();
   }
@@ -500,9 +502,8 @@ void RenderWidget::CompleteInit() {
   if (webwidget_ && is_threaded_compositing_enabled_) {
     webwidget_->enterForceCompositingMode(true);
   }
-  if (compositor_) {
-    compositor_->setSurfaceReady();
-  }
+  if (compositor_)
+    StartCompositor();
   DoDeferredUpdate();
 
   Send(new ViewHostMsg_RenderViewReady(routing_id_));
@@ -880,6 +881,9 @@ bool RenderWidget::ForceCompositingModeEnabled() {
 }
 
 scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
+  // For widgets that are never visible, we don't start the compositor, so we
+  // never get a request for a cc::OutputSurface.
+  DCHECK(!never_visible_);
 
 #if defined(OS_ANDROID)
   if (SynchronousCompositorFactory* factory =
@@ -1865,7 +1869,7 @@ void RenderWidget::initializeLayerTreeView() {
 
   compositor_->setViewportSize(size_, physical_backing_size_);
   if (init_complete_)
-    compositor_->setSurfaceReady();
+    StartCompositor();
 }
 
 blink::WebLayerTreeView* RenderWidget::layerTreeView() {
@@ -2658,6 +2662,14 @@ void RenderWidget::didHandleGestureEvent(
 #endif
 }
 
+void RenderWidget::StartCompositor() {
+  // For widgets that are never visible, we don't need the compositor to run
+  // at all.
+  if (never_visible_)
+    return;
+  compositor_->setSurfaceReady();
+}
+
 void RenderWidget::SchedulePluginMove(const WebPluginGeometry& move) {
   size_t i = 0;
   for (; i < plugin_window_moves_.size(); ++i) {