Add non-member non-mutating methods for common gfx::Rect operations.

cc/draw_quad.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "cc/draw_quad.h"
 
 #include "base/logging.h"
 #include "cc/checkerboard_draw_quad.h"
@@ skipping 25 matching lines @@
 {
     if (opacity() != 1)
         return gfx::Rect();
     if (m_sharedQuadState->opaque && m_quadOpaque)
         return m_quadRect;
     return m_opaqueRect;
 }
 
 void DrawQuad::setQuadVisibleRect(gfx::Rect quadVisibleRect)
 {
-    m_quadVisibleRect = quadVisibleRect;
-    m_quadVisibleRect.Intersect(m_quadRect);
+    m_quadVisibleRect = gfx::Intersection(quadVisibleRect, m_quadRect);
 }
 
 unsigned DrawQuad::size() const
 {
     switch (material()) {
     case Checkerboard:
         return sizeof(CheckerboardDrawQuad);
     case DebugBorder:
         return sizeof(DebugBorderDrawQuad);
     case IOSurfaceContent:
@@ skipping 33 matching lines @@
     return copyQuad.Pass();
 }
 
 void DrawQuad::setSharedQuadState(const SharedQuadState* sharedQuadState)
 {
     m_sharedQuadState = sharedQuadState;
     m_sharedQuadStateId = sharedQuadState->id;
 }
 
 }