[Master/Overview CL] Make PageScaleFactor work for oopif subframe.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 86c716946a95da937550d1af9fa08e64d7184386..3d20600ccc2bef7990cb12573b5d7c1c4195d62f 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1077,9 +1077,14 @@ bool LayerImpl::IsHidden() const {
 }
 
 float LayerImpl::GetIdealContentsScale() const {
-  float page_scale = IsAffectedByPageScale()
-                         ? layer_tree_impl()->current_page_scale_factor()
-                         : 1.f;
+  // When there is no page scale layer we could be rendering a sub-frame in
+  // a separate process, so we should include the current page scale factor
+  // for creating the raster scale.
+  // TODO(wjmaclean): Re-word this comment in a more CC-like manner.
+  float page_scale =
+      (!layer_tree_impl()->PageScaleLayer() || IsAffectedByPageScale())
+          ? layer_tree_impl()->current_page_scale_factor()
+          : 1.f;
   float device_scale = layer_tree_impl()->device_scale_factor();
 
   float default_scale = page_scale * device_scale;