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

gpu/command_buffer/client/cmd_buffer_helper.cc

Index: gpu/command_buffer/client/cmd_buffer_helper.cc
===================================================================
--- gpu/command_buffer/client/cmd_buffer_helper.cc	(revision 34314)
+++ gpu/command_buffer/client/cmd_buffer_helper.cc	(working copy)
@@ -35,9 +35,9 @@
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 
-namespace command_buffer {
+namespace gpu {
 
-using command_buffer::CommandBuffer;
+using gpu::CommandBuffer;
 
 CommandBufferHelper::CommandBufferHelper(CommandBuffer* command_buffer)
     : command_buffer_(command_buffer),
@@ -188,4 +188,4 @@
   return static_cast<parse_error::ParseError>(parse_error);
 }
 
-}  // namespace command_buffer
+}  // namespace gpu