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

content/renderer/render_widget_fullscreen_pepper.cc

Index: content/renderer/render_widget_fullscreen_pepper.cc
diff --git a/content/renderer/render_widget_fullscreen_pepper.cc b/content/renderer/render_widget_fullscreen_pepper.cc
index b14c9e509496de789e56d4c5f125ba355798efeb..58cb9dae1f98c667a979dddf0c1f5efaca13eaec 100644
--- a/content/renderer/render_widget_fullscreen_pepper.cc
+++ b/content/renderer/render_widget_fullscreen_pepper.cc
@@ -508,7 +508,8 @@ void RenderWidgetFullscreenPepper::OnResize(const gfx::Size& size,
                                             const gfx::Rect& resizer_rect,
                                             bool is_fullscreen) {
   if (context_) {
-    gfx::Size pixel_size = gfx::ToFlooredSize(size.Scale(deviceScaleFactor()));
+    gfx::Size pixel_size = gfx::ToFlooredSize(
+        gfx::ScaleSize(size, deviceScaleFactor()));
     context_->reshape(pixel_size.width(), pixel_size.height());
     context_->viewport(0, 0, pixel_size.width(), pixel_size.height());
   }
@@ -601,7 +602,8 @@ const float kTexCoords[] = {
 }  // anonymous namespace
 
 bool RenderWidgetFullscreenPepper::InitContext() {
-  gfx::Size pixel_size = gfx::ToFlooredSize(size().Scale(deviceScaleFactor()));
+  gfx::Size pixel_size = gfx::ToFlooredSize(
+      gfx::ScaleSize(size(), deviceScaleFactor()));
   context_->reshape(pixel_size.width(), pixel_size.height());
   context_->viewport(0, 0, pixel_size.width(), pixel_size.height());