ui: Make gfx::Size::Scale() mutate the class. Add gfx::ScaleSize() similar to Rect/Point.

chrome/browser/thumbnails/render_widget_snapshot_taker.cc

Index: chrome/browser/thumbnails/render_widget_snapshot_taker.cc
diff --git a/chrome/browser/thumbnails/render_widget_snapshot_taker.cc b/chrome/browser/thumbnails/render_widget_snapshot_taker.cc
index cd0dbd371635a9904f09f1dd4ae95471bbdd4ec8..184ccebe46855b9762e2421ac1a8508b0d03c82f 100644
--- a/chrome/browser/thumbnails/render_widget_snapshot_taker.cc
+++ b/chrome/browser/thumbnails/render_widget_snapshot_taker.cc
@@ -48,7 +48,7 @@ void RenderWidgetSnapshotTaker::AskForSnapshot(
   float scale_factor = ui::GetScaleFactorScale(ui::GetScaleFactorForNativeView(
       renderer->GetView()->GetNativeView()));
   gfx::Size desired_size_in_pixel = gfx::ToFlooredSize(
-      desired_size.Scale(scale_factor));
+      gfx::ScaleSize(desired_size, scale_factor));
   scoped_ptr<TransportDIB> thumbnail_dib(TransportDIB::Create(
       desired_size_in_pixel.GetArea() * 4, sequence_num));