Revert of [#7] Pass gfx structs by const ref (gfx::Size)

cc/resources/resource_pool.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 "cc/resources/resource_pool.h"
 
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/scoped_resource.h"
 
 namespace cc {
@@ skipping 17 matching lines @@
     busy_resources_.pop_front();
   }
 
   SetResourceUsageLimits(0, 0, 0);
   DCHECK_EQ(0u, unused_resources_.size());
   DCHECK_EQ(0u, memory_usage_bytes_);
   DCHECK_EQ(0u, unused_memory_usage_bytes_);
   DCHECK_EQ(0u, resource_count_);
 }
 
-scoped_ptr<ScopedResource> ResourcePool::AcquireResource(
-    const gfx::Size& size) {
+scoped_ptr<ScopedResource> ResourcePool::AcquireResource(gfx::Size size) {
   for (ResourceList::iterator it = unused_resources_.begin();
        it != unused_resources_.end();
        ++it) {
     ScopedResource* resource = *it;
     DCHECK(resource_provider_->CanLockForWrite(resource->id()));
 
     if (resource->size() != size)
       continue;
 
     unused_resources_.erase(it);
@@ skipping 75 matching lines @@
     }
   }
 }
 
 void ResourcePool::DidFinishUsingResource(ScopedResource* resource) {
   unused_memory_usage_bytes_ += resource->bytes();
   unused_resources_.push_back(resource);
 }
 
 }  // namespace cc