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

cc/layer_tree_host_unittest.cc

Index: cc/layer_tree_host_unittest.cc
diff --git a/cc/layer_tree_host_unittest.cc b/cc/layer_tree_host_unittest.cc
index b8c92c2e07e47d291f9b7310c9c432c0af27e082..d5d0b39378a19db7e0cd716aac0be3a6b7f7e710 100644
--- a/cc/layer_tree_host_unittest.cc
+++ b/cc/layer_tree_host_unittest.cc
@@ -1339,8 +1339,7 @@ public:
         EXPECT_RECT_EQ(gfx::Rect(0, 0, 60, 60), root->renderSurface()->contentRect());
 
         // The content bounds of the child should be scaled.
-        gfx::Size childBoundsScaled = child->bounds();
-        childBoundsScaled = gfx::ToRoundedSize(childBoundsScaled.Scale(1.5));
+        gfx::Size childBoundsScaled = gfx::ToCeiledSize(gfx::ScaleSize(child->bounds(), 1.5));
         EXPECT_EQ(childBoundsScaled, child->contentBounds());
 
         WebTransformationMatrix scaleTransform;
@@ -2187,7 +2186,7 @@ public:
     virtual void beginTest() OVERRIDE
     {
         gfx::Size viewportSize(10, 10);
-        gfx::Size deviceViewportSize = gfx::ToCeiledSize(viewportSize.Scale(m_deviceScaleFactor));
+        gfx::Size deviceViewportSize = gfx::ToCeiledSize(gfx::ScaleSize(viewportSize, m_deviceScaleFactor));
         m_layerTreeHost->setViewportSize(viewportSize, deviceViewportSize);
 
         m_layerTreeHost->setDeviceScaleFactor(m_deviceScaleFactor);
@@ -2347,7 +2346,7 @@ public:
     virtual void beginTest() OVERRIDE
     {
         gfx::Size viewportSize(10, 10);
-        gfx::Size deviceViewportSize = gfx::ToCeiledSize(viewportSize.Scale(m_deviceScaleFactor));
+        gfx::Size deviceViewportSize = gfx::ToCeiledSize(gfx::ScaleSize(viewportSize, m_deviceScaleFactor));
         m_layerTreeHost->setViewportSize(viewportSize, deviceViewportSize);
 
         m_layerTreeHost->setDeviceScaleFactor(m_deviceScaleFactor);