GPU: 'Pass' SharedMemory when possible.

mojo/services/gles2/command_buffer_impl.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 "mojo/services/gles2/command_buffer_impl.h"
 
 #include "base/bind.h"
 #include "base/memory/shared_memory.h"
 
 #include "gpu/command_buffer/common/constants.h"
@@ skipping 125 matching lines @@
 
 void CommandBufferImpl::MakeProgress(int32_t last_get_offset) {
   // TODO(piman): handle out-of-order.
   AllocationScope scope;
   sync_client_->DidMakeProgress(command_buffer_->GetState());
 }
 
 void CommandBufferImpl::RegisterTransferBuffer(int32_t id,
                                                const ShmHandle& transfer_buffer,
                                                uint32_t size) {
-  bool read_only = false;
-  base::SharedMemory shared_memory(transfer_buffer, read_only);
-  command_buffer_->RegisterTransferBuffer(id, &shared_memory, size);
+  // Duplicate the shared memory for this process.
+  base::SharedMemory shared_memory(transfer_buffer, false);
+  base::SharedMemoryHandle duped_shared_memory_handle;
+  if (!shared_memory.ShareToProcess(base::GetCurrentProcessHandle(),
+                                    &duped_shared_memory_handle)) {
+    DVLOG(0) << "Failed to duplicate shared memory handle.";
+    return;
+  }
+  scoped_ptr<base::SharedMemory> duped_shared_memory(
+      new base::SharedMemory(duped_shared_memory_handle, false));
+
+  // Map the shared memory into this process. This validates the size.
+  if (!duped_shared_memory->Map(size)) {
+    DVLOG(0) << "Failed to map shared memory.";
+    return;
+  }
+
+  command_buffer_->RegisterTransferBuffer(id, duped_shared_memory.Pass(), size);
 }
 
 void CommandBufferImpl::DestroyTransferBuffer(int32_t id) {
   command_buffer_->DestroyTransferBuffer(id);
 }
 
 void CommandBufferImpl::Echo(const Callback<void()>& callback) {
   callback.Run();
 }
 
 void CommandBufferImpl::RequestAnimationFrames() {
   timer_.Start(FROM_HERE,
                base::TimeDelta::FromMilliseconds(16),
                this,
                &CommandBufferImpl::DrawAnimationFrame);
 }
 
 void CommandBufferImpl::CancelAnimationFrames() { timer_.Stop(); }
 
 void CommandBufferImpl::OnParseError() {
   gpu::CommandBuffer::State state = command_buffer_->GetState();
   client_->LostContext(state.context_lost_reason);
 }
 
 void CommandBufferImpl::DrawAnimationFrame() { client_->DrawAnimationFrame(); }
 
 }  // namespace services
 }  // namespace mojo