Implements core logic for Pixel Canvas

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 4bd56de2d6d39abb5ac369160dc6c13dce813ba9..09bfc40ca1d8c142522bb1cb61f4cfe3d5e584d8 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -320,6 +320,8 @@ class CC_EXPORT LayerTreeHost
   void SetDeviceScaleFactor(float device_scale_factor);
   float device_scale_factor() const { return device_scale_factor_; }
 
+  void SetRecordingScaleFactor(float recording_scale_factor);
+
   void SetPaintedDeviceScaleFactor(float painted_device_scale_factor);
   float painted_device_scale_factor() const {
     return painted_device_scale_factor_;
@@ -496,6 +498,8 @@ class CC_EXPORT LayerTreeHost
 
   void RequestBeginMainFrameNotExpected(bool new_state);
 
+  float recording_scale_factor() const { return recording_scale_factor_; }
+
  protected:
   LayerTreeHost(InitParams* params, CompositorMode mode);
 
@@ -603,6 +607,7 @@ class CC_EXPORT LayerTreeHost
 
   float device_scale_factor_ = 1.f;
   float painted_device_scale_factor_ = 1.f;
+  float recording_scale_factor_ = 1.f;
   float page_scale_factor_ = 1.f;
   float min_page_scale_factor_ = 1.f;
   float max_page_scale_factor_ = 1.f;