Added a unique command buffer ID for command buffers.

mojo/gles2/command_buffer_client_impl.cc

Index: mojo/gles2/command_buffer_client_impl.cc
diff --git a/mojo/gles2/command_buffer_client_impl.cc b/mojo/gles2/command_buffer_client_impl.cc
index b639f6e40472b2337f4fc5f3ec5040ea992ec3b7..b419b766231d436b79c5ddaa684061d9b894571e 100644
--- a/mojo/gles2/command_buffer_client_impl.cc
+++ b/mojo/gles2/command_buffer_client_impl.cc
@@ -393,4 +393,16 @@ bool CommandBufferClientImpl::IsGpuChannelLost() {
   return false;
 }
 
+gpu::CommandBufferNamespace CommandBufferClientImpl::GetNamespaceID() const {
+  return gpu::kCommandBufferNamespace_Mojo;
+}
+
+uint64_t CommandBufferClientImpl::GetCommandBufferID() const {
+  // TODO (rjkroege): This must correspond to the command buffer ID on the
+  // server side. Most likely a combination of the client-specific integer and
+  // the connect id.
+  NOTIMPLEMENTED();
+  return 0;
+}
+
 }  // namespace gles2