Made Blink aware of top controls offset (Chromium-side)

content/renderer/gpu/render_widget_compositor.h

Index: content/renderer/gpu/render_widget_compositor.h
diff --git a/content/renderer/gpu/render_widget_compositor.h b/content/renderer/gpu/render_widget_compositor.h
index fc8d60ed9af4395661045928ef1efd09e0d700e4..28de28e1529c9121b504b5d3f262d7aeff481898 100644
--- a/content/renderer/gpu/render_widget_compositor.h
+++ b/content/renderer/gpu/render_widget_compositor.h
@@ -50,7 +50,6 @@ class RenderWidgetCompositor : public blink::WebLayerTreeView,
   void UpdateTopControlsState(cc::TopControlsState constraints,
                               cc::TopControlsState current,
                               bool animate);
-  void SetTopControlsLayoutHeight(float top_controls_layout_height);
   void SetNeedsRedrawRect(gfx::Rect damage_rect);
   // Like setNeedsRedraw but forces the frame to be drawn, without early-outs.
   // Redraw will be forced after the next commit
@@ -123,6 +122,7 @@ class RenderWidgetCompositor : public blink::WebLayerTreeView,
   virtual void setShowDebugBorders(bool show);
   virtual void setContinuousPaintingEnabled(bool enabled);
   virtual void setShowScrollBottleneckRects(bool show);
+  virtual void setTopControlsContentOffset(int);

[bokan, 2014/08/28 18:42:45]

It feels strange that this class ends up with two of the same named methods
(with case diff) but they come from separate interfaces where it makes sense in
those contexts. WDYT?

[aelias_OOO_until_Jul13, 2014/08/29 04:37:01]

Could you instead add an additional parameter to applyScrollAndScale and rename
that to something else (applyImplThreadDeltas?).  Aside from this issue, I find
bundling related state into the same method can help avoid clamping-related bugs
(avoids problems like you first make the viewport smaller, scroll clamped, then
you adjust the scroll...)

[bokan, 2014/08/29 18:02:14]

I had a FIXME to do just that. My concern was that the inner/outer viewport
scroll offsets are set before applyScrollAndScale and so I was worried about
clamping and I was a bit hesitant to change around the order these things happen
in for this CL. I do feel like I understand these paths better now so I'll take
another look here.

[bokan, 2014/09/02 18:57:16]

Done.

 
   // cc::LayerTreeHostClient implementation.
   virtual void WillBeginMainFrame(int frame_id) OVERRIDE;
@@ -131,6 +131,7 @@ class RenderWidgetCompositor : public blink::WebLayerTreeView,
   virtual void Layout() OVERRIDE;
   virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float page_scale) OVERRIDE;
+  virtual void SetTopControlsContentOffset(int offset) OVERRIDE;
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface(bool fallback)
       OVERRIDE;
   virtual void DidInitializeOutputSurface() OVERRIDE;