GPU: 'Pass' SharedMemory when possible.

mojo/services/gles2/command_buffer_impl.cc

Index: mojo/services/gles2/command_buffer_impl.cc
diff --git a/mojo/services/gles2/command_buffer_impl.cc b/mojo/services/gles2/command_buffer_impl.cc
index 71df2c5e7a9d9ed14cb0446528f7a7cdd42f6508..3ffa3946582edeb38325d861bc9efd97173c8f03 100644
--- a/mojo/services/gles2/command_buffer_impl.cc
+++ b/mojo/services/gles2/command_buffer_impl.cc
@@ -143,9 +143,24 @@ void CommandBufferImpl::MakeProgress(int32_t last_get_offset) {
 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) {