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

cc/direct_renderer.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/direct_renderer.h"
 
 #include <vector>
 
@@ skipping 168 matching lines @@
         WebTransformationMatrix inverseTransformToRoot = frame.currentRenderPass->transformToRootTarget().inverse();
         gfx::RectF damageRectInRenderPassSpace = MathUtil::projectClippedRect(inverseTransformToRoot, cc::FloatRect(frame.rootDamageRect));
         frame.scissorRectInRenderPassSpace.Intersect(damageRectInRenderPassSpace);
     }
 
     enableScissorTestRect(moveScissorToWindowSpace(frame, frame.scissorRectInRenderPassSpace));
     clearFramebuffer(frame);
 
     const QuadList& quadList = renderPass->quadList();
     for (QuadList::constBackToFrontIterator it = quadList.backToFrontBegin(); it != quadList.backToFrontEnd(); ++it) {
-        gfx::RectF quadScissorRect = frame.scissorRectInRenderPassSpace;
-        quadScissorRect.Intersect((*it)->clippedRectInTarget());
+        gfx::RectF quadScissorRect = gfx::IntersectRects(frame.scissorRectInRenderPassSpace, (*it)->clippedRectInTarget());
         if (!quadScissorRect.IsEmpty()) {
             enableScissorTestRect(moveScissorToWindowSpace(frame, quadScissorRect));
             drawQuad(frame, *it);
         }
     }
 
     CachedTexture* texture = m_renderPassTextures.get(renderPass->id());
     if (texture)
         texture->setIsComplete(!renderPass->hasOcclusionFromOutsideTargetSurface());
 }
@@ skipping 30 matching lines @@
     return cc::IntSize(pass->outputRect().size());
 }
 
 // static
 GLenum DirectRenderer::renderPassTextureFormat(const RenderPass*)
 {
     return GL_RGBA;
 }
 
 }