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

content/common/gpu/client/gpu_memory_buffer_impl_win.cc

Index: content/common/gpu/client/gpu_memory_buffer_impl_win.cc
diff --git a/content/common/gpu/client/gpu_memory_buffer_impl_win.cc b/content/common/gpu/client/gpu_memory_buffer_impl_win.cc
index 8da027bbb5b0bb475b10e31c3b8ed5fdfe4a708d..7c6cbfafed9c65c4c829fce0e41a6da36ecc734e 100644
--- a/content/common/gpu/client/gpu_memory_buffer_impl_win.cc
+++ b/content/common/gpu/client/gpu_memory_buffer_impl_win.cc
@@ -32,15 +32,16 @@ void GpuMemoryBufferImpl::AllocateForChildProcess(
     unsigned internalformat,
     unsigned usage,
     base::ProcessHandle child_process,
-    gfx::GpuMemoryBufferHandle* handle) {
+    gfx::GpuMemoryBufferHandle* handle,
+    const base::Closure& allocate_callback) {
+  handle->type = gfx::EMPTY_BUFFER;
   if (GpuMemoryBufferImplShm::IsConfigurationSupported(
           size, internalformat, usage)) {
     GpuMemoryBufferImplShm::AllocateSharedMemoryForChildProcess(
         size, internalformat, child_process, handle);
-    return;
   }
 
-  handle->type = gfx::EMPTY_BUFFER;
+  allocate_callback.Run();
 }
 
 // static