Add some Mojo C thunks used by cc when turning on impl-side painting.

mojo/public/c/gles2/chromium_image.h

Index: mojo/public/c/gles2/chromium_image.h
diff --git a/mojo/public/c/gles2/occlusion_query_ext.h b/mojo/public/c/gles2/chromium_image.h
similarity index 70%
copy from mojo/public/c/gles2/occlusion_query_ext.h
copy to mojo/public/c/gles2/chromium_image.h
index 592207773d329ab66a908f26464c91ee42c830c9..c73ee22863910ac1d82ce3d63d1e9932190de0b2 100644
--- a/mojo/public/c/gles2/occlusion_query_ext.h
+++ b/mojo/public/c/gles2/chromium_image.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef MOJO_PUBLIC_C_GLES2_OCCLUSION_QUERY_EXT_H_
-#define MOJO_PUBLIC_C_GLES2_OCCLUSION_QUERY_EXT_H_
+#ifndef MOJO_PUBLIC_C_GLES2_CHROMIUM_IMAGE_H_
+#define MOJO_PUBLIC_C_GLES2_CHROMIUM_IMAGE_H_
 
 // Note: This header should be compilable as C.
 
@@ -14,17 +14,19 @@
 #include "mojo/public/c/gles2/gles2_types.h"
 #include "mojo/public/c/system/types.h"
 
+extern "C" typedef struct _ClientBuffer* ClientBuffer;
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #define VISIT_GL_CALL(Function, ReturnType, PARAMETERS, ARGUMENTS) \
   MOJO_GLES2_EXPORT ReturnType GL_APIENTRY gl##Function PARAMETERS;
-#include "mojo/public/c/gles2/gles2_call_visitor_occlusion_query_ext_autogen.h"
+#include "mojo/public/c/gles2/gles2_call_visitor_chromium_image_autogen.h"
 #undef VISIT_GL_CALL
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
-#endif  // MOJO_PUBLIC_C_GLES2_OCCLUSION_QUERY_EXT_H_
+#endif  // MOJO_PUBLIC_C_GLES2_CHROMIUM_IMAGE_H_