Delay the response to ChildProcessHostMsg_SyncAllocateGpuMemoryBuffer via a callback to allow for b…

content/common/gpu/client/gpu_memory_buffer_impl_shm.cc

 // Copyright 2013 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 "content/common/gpu/client/gpu_memory_buffer_impl_shm.h"
 
 #include "base/numerics/safe_math.h"
 #include "ui/gl/gl_bindings.h"
 
 namespace content {
 
 GpuMemoryBufferImplShm::GpuMemoryBufferImplShm(const gfx::Size& size,
                                                unsigned internalformat)
     : GpuMemoryBufferImpl(size, internalformat) {}
 
 GpuMemoryBufferImplShm::~GpuMemoryBufferImplShm() {}
 
 // static
 void GpuMemoryBufferImplShm::AllocateSharedMemoryForChildProcess(
     const gfx::Size& size,
     unsigned internalformat,
     base::ProcessHandle child_process,
-    gfx::GpuMemoryBufferHandle* handle) {
+    const AllocationCallback& callback) {
   DCHECK(IsLayoutSupported(size, internalformat));
+  gfx::GpuMemoryBufferHandle handle;
   base::SharedMemory shared_memory;
   if (!shared_memory.CreateAnonymous(size.GetArea() *
                                      BytesPerPixel(internalformat))) {
-    handle->type = gfx::EMPTY_BUFFER;
+    handle.type = gfx::EMPTY_BUFFER;
     return;
   }
-  handle->type = gfx::SHARED_MEMORY_BUFFER;
-  shared_memory.GiveToProcess(child_process, &handle->handle);
+  handle.type = gfx::SHARED_MEMORY_BUFFER;
+  shared_memory.GiveToProcess(child_process, &handle.handle);
+  callback.Run(handle);
 }
 
 // static
 bool GpuMemoryBufferImplShm::IsLayoutSupported(const gfx::Size& size,
                                                unsigned internalformat) {
   base::CheckedNumeric<int> buffer_size = size.width();
   buffer_size *= size.height();
   buffer_size *= BytesPerPixel(internalformat);
   return buffer_size.IsValid();
 }
@@ skipping 55 matching lines @@
 }
 
 gfx::GpuMemoryBufferHandle GpuMemoryBufferImplShm::GetHandle() const {
   gfx::GpuMemoryBufferHandle handle;
   handle.type = gfx::SHARED_MEMORY_BUFFER;
   handle.handle = shared_memory_->handle();
   return handle;
 }
 
 }  // namespace content