Make PageScaleFactor work for oopif subframes.

cc/trees/layer_tree.h

Index: cc/trees/layer_tree.h
diff --git a/cc/trees/layer_tree.h b/cc/trees/layer_tree.h
index 5ac3f690ebf20964f1c93cbb0c448cf610f703ea..d57213e809683c44bee2f1256d07aae95696ce45 100644
--- a/cc/trees/layer_tree.h
+++ b/cc/trees/layer_tree.h
@@ -90,7 +90,11 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
   void SetPageScaleFactorAndLimits(float page_scale_factor,
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
+  void SetSubframePageScaleFactor(float sub_frame_page_scale_factor);
   float page_scale_factor() const { return inputs_.page_scale_factor; }
+  float subframe_page_scale_factor() const {
+    return inputs_.subframe_page_scale_factor;
+  }
   float min_page_scale_factor() const { return inputs_.min_page_scale_factor; }
   float max_page_scale_factor() const { return inputs_.max_page_scale_factor; }
 
@@ -239,6 +243,7 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
     float device_scale_factor;
     float painted_device_scale_factor;
     float page_scale_factor;
+    float subframe_page_scale_factor;
     float min_page_scale_factor;
     float max_page_scale_factor;
     gfx::ColorSpace device_color_space;