Added CommandBufferClient, CommandBufferStub and some IPC messages....

gpu/command_buffer/common/cmd_buffer_common.cc

Index: gpu/command_buffer/common/cmd_buffer_common.cc
===================================================================
--- gpu/command_buffer/common/cmd_buffer_common.cc	(revision 34314)
+++ gpu/command_buffer/common/cmd_buffer_common.cc	(working copy)
@@ -35,7 +35,7 @@
 
 #include "gpu/command_buffer/common/cmd_buffer_common.h"
 
-namespace command_buffer {
+namespace gpu {
 namespace cmd {
 
 const char* GetCommandName(CommandId command_id) {
@@ -52,6 +52,6 @@
 }
 
 }  // namespace cmd
-}  // namespace command_buffer
+}  // namespace gpu