Implements core logic for Pixel Canvas

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 7c5941af90e53a031f1c8680069d8ba4b8a36bc5..78865db1743acd6a28d0142656221f117bf9916e 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -1037,6 +1037,12 @@ void LayerTreeHost::SetDeviceScaleFactor(float device_scale_factor) {
   SetNeedsCommit();
 }
 
+void LayerTreeHost::SetRecordingScaleFactor(float recording_scale_factor) {
+  if (recording_scale_factor_ == recording_scale_factor)
+    return;
+  recording_scale_factor_ = recording_scale_factor;
+}
+
 void LayerTreeHost::SetPaintedDeviceScaleFactor(
     float painted_device_scale_factor) {
   if (painted_device_scale_factor_ == painted_device_scale_factor)