Allow using a larger-than-necessary texture as cached render pass backing

cc/render_surface_impl.cc

 // Copyright 2011 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 "cc/render_surface_impl.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
@@ skipping 207 matching lines @@
     LayerImpl* maskLayer = m_owningLayer->maskLayer();
     if (maskLayer && (!maskLayer->drawsContent() || maskLayer->bounds().IsEmpty()))
         maskLayer = 0;
 
     if (!maskLayer && forReplica) {
         maskLayer = m_owningLayer->replicaLayer()->maskLayer();
         if (maskLayer && (!maskLayer->drawsContent() || maskLayer->bounds().IsEmpty()))
             maskLayer = 0;
     }
 
-    float maskTexCoordScaleX = 1;
-    float maskTexCoordScaleY = 1;
-    float maskTexCoordOffsetX = 0;
-    float maskTexCoordOffsetY = 0;
+    gfx::RectF mask_uv_rect(0.0f, 0.0f, 1.0f, 1.0f);
     if (maskLayer) {
-        maskTexCoordScaleX = contentRect().width() / maskLayer->contentsScaleX() / maskLayer->bounds().width();
-        maskTexCoordScaleY = contentRect().height() / maskLayer->contentsScaleY() / maskLayer->bounds().height();
-        maskTexCoordOffsetX = static_cast<float>(contentRect().x()) / contentRect().width() * maskTexCoordScaleX;
-        maskTexCoordOffsetY = static_cast<float>(contentRect().y()) / contentRect().height() * maskTexCoordScaleY;
+        mask_uv_rect.set_width(contentRect().width() / maskLayer->contentsScaleX() / maskLayer->bounds().width());
+        mask_uv_rect.set_height(contentRect().height() / maskLayer->contentsScaleY() / maskLayer->bounds().height());
+        mask_uv_rect.set_x(static_cast<float>(contentRect().x()) / contentRect().width() * mask_uv_rect.width());
+        mask_uv_rect.set_y(static_cast<float>(contentRect().y()) / contentRect().height() * mask_uv_rect.height());
     }
 
     ResourceProvider::ResourceId maskResourceId = maskLayer ? maskLayer->contentsResourceId() : 0;
     gfx::Rect contentsChangedSinceLastFrame = contentsChanged() ? m_contentRect : gfx::Rect();
 
     scoped_ptr<RenderPassDrawQuad> quad = RenderPassDrawQuad::Create();
     quad->SetNew(sharedQuadState, contentRect(), renderPassId, forReplica, maskResourceId, contentsChangedSinceLastFrame,
-                 maskTexCoordScaleX, maskTexCoordScaleY, maskTexCoordOffsetX, maskTexCoordOffsetY);
+                 mask_uv_rect);
     quadSink.append(quad.PassAs<DrawQuad>(), appendQuadsData);
 }
 
 }  // namespace cc