Revert of Remove fallback tick software draw.

android_webview/browser/browser_view_renderer.h

Index: android_webview/browser/browser_view_renderer.h
diff --git a/android_webview/browser/browser_view_renderer.h b/android_webview/browser/browser_view_renderer.h
index 4d31689829ef4c2d727b09fa143a365e63aa39f3..21c28c8f97da3ef4ad14aef6cfa08917f44ece72 100644
--- a/android_webview/browser/browser_view_renderer.h
+++ b/android_webview/browser/browser_view_renderer.h
@@ -120,12 +120,18 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
  private:
   void SetTotalRootLayerScrollOffset(const gfx::Vector2dF& new_value_dip);
   bool CanOnDraw();
+  // Posts an invalidate with fallback tick. All invalidates posted while an
+  // invalidate is pending will be posted as a single invalidate after the
+  // pending invalidate is done.
+  void PostInvalidateWithFallback();
+  void CancelFallbackTick();
   void UpdateCompositorIsActive();
   bool CompositeSW(SkCanvas* canvas);
   scoped_refptr<base::trace_event::ConvertableToTraceFormat>
   RootLayerStateAsValue(const gfx::Vector2dF& total_scroll_offset_dip,
                         const gfx::SizeF& scrollable_size_dip);
 
+  bool CompositeHw();
   void ReturnUnusedResource(scoped_ptr<ChildFrame> frame);
   void ReturnResourceFromParent();
 
@@ -136,6 +142,11 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
   void PostFallbackTick();
   void FallbackTickFired();
 
+  // Force invoke the compositor to run produce a 1x1 software frame that is
+  // immediately discarded. This is a hack to force invoke parts of the
+  // compositor that are not directly exposed here.
+  void ForceFakeCompositeSW();
+
   gfx::Vector2d max_scroll_offset() const;
 
   void UpdateMemoryPolicy();
@@ -168,6 +179,10 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
   gfx::Vector2d last_on_draw_scroll_offset_;
   gfx::Rect last_on_draw_global_visible_rect_;
 
+  base::CancelableClosure post_fallback_tick_;
+  base::CancelableClosure fallback_tick_fired_;
+  bool fallback_tick_pending_;
+
   gfx::Size size_;
 
   gfx::SizeF scrollable_size_dip_;