(Reland) Discard compositor frames from unloaded web content

content/test/test_render_view_host.h

Index: content/test/test_render_view_host.h
diff --git a/content/test/test_render_view_host.h b/content/test/test_render_view_host.h
index 252a22dd5bf4aa500438a0b1c2b038cb303ea6d0..6a9a4f58b6746315b24ba00ddd5700c24a7038e8 100644
--- a/content/test/test_render_view_host.h
+++ b/content/test/test_render_view_host.h
@@ -111,6 +111,7 @@ class TestRenderWidgetHostView : public RenderWidgetHostViewBase {
   bool is_showing() const { return is_showing_; }
   bool is_occluded() const { return is_occluded_; }
   bool did_swap_compositor_frame() const { return did_swap_compositor_frame_; }
+  void reset_did_swap_compositor_frame() { did_swap_compositor_frame_ = false; }
 
  protected:
   RenderWidgetHostImpl* rwh_;