Add logic to ResourceProvider to correctly lock GpuMemoryBuffer Resources.

cc/resources/resource_provider.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_provider.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1024 matching lines @@
       resource_(resource_provider->LockForWrite(resource_id)) {
   ResourceProvider::PopulateSkBitmapWithResource(&sk_bitmap_, resource_);
   DCHECK(valid());
 }
 
 ResourceProvider::ScopedWriteLockSoftware::~ScopedWriteLockSoftware() {
   DCHECK(thread_checker_.CalledOnValidThread());
   resource_provider_->UnlockForWrite(resource_);
 }
 
+ResourceProvider::ScopedReadLockGpuMemoryBuffer::ScopedReadLockGpuMemoryBuffer(
+    ResourceProvider* resource_provider,
+    ResourceId resource_id)
+    : resource_provider_(resource_provider),
+      resource_id_(resource_id),
+      resource_(resource_provider->LockForRead(resource_id)) {
+  DCHECK(IsGpuResourceType(resource_->type));

[ccameron, 2016/05/17 03:36:38]

This will need to create the GpuMemoryBuffer from the (not yet existing)
CreateFromClientId method added in https://codereview.chromium.org/1975023002/.

We already have the plumbing for the GpuMemoryBufferId, but I am still working
on plumbing the gpu_memory_buffer_factor_client_id through.

[erikchen, 2016/05/17 22:13:20]

N/A

+}
+
+ResourceProvider::ScopedReadLockGpuMemoryBuffer::
+    ~ScopedReadLockGpuMemoryBuffer() {
+  resource_provider_->UnlockForRead(resource_id_);
+}
+
+bool ResourceProvider::ScopedReadLockGpuMemoryBuffer::
+    IsInUseByMacOSWindowServer() const {
+  if (!resource_->gpu_memory_buffer)
+    return false;
+  return resource_->gpu_memory_buffer->IsInUseByMacOSWindowServer();
+}
+
 ResourceProvider::ScopedWriteLockGpuMemoryBuffer::
     ScopedWriteLockGpuMemoryBuffer(ResourceProvider* resource_provider,
                                    ResourceId resource_id)
     : resource_provider_(resource_provider),
       resource_(resource_provider->LockForWrite(resource_id)) {
   DCHECK(IsGpuResourceType(resource_->type));
   gpu_memory_buffer_ = std::move(resource_->gpu_memory_buffer);
   resource_->gpu_memory_buffer = nullptr;
 }
 
@@ skipping 913 matching lines @@
 
     const int kImportance = 2;
     pmd->CreateSharedGlobalAllocatorDump(guid);
     pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
   }
 
   return true;
 }
 
 }  // namespace cc