Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

gpu/command_buffer/client/gles2_c_lib_autogen.h

Index: gpu/command_buffer/client/gles2_c_lib_autogen.h
diff --git a/gpu/command_buffer/client/gles2_c_lib_autogen.h b/gpu/command_buffer/client/gles2_c_lib_autogen.h
index 6d8653953d168294352465d11fe2fee541624ace..448c182e8ada58a873ddcf4a605d0e74fefaf2c0 100644
--- a/gpu/command_buffer/client/gles2_c_lib_autogen.h
+++ b/gpu/command_buffer/client/gles2_c_lib_autogen.h
@@ -636,6 +636,12 @@ void GLES2DrawElementsInstancedANGLE(
 void GLES2VertexAttribDivisorANGLE(GLuint index, GLuint divisor) {
   gles2::GetGLContext()->VertexAttribDivisorANGLE(index, divisor);
 }
+void GLES2DiscardBackbufferCHROMIUM() {
+  gles2::GetGLContext()->DiscardBackbufferCHROMIUM();
+}
+void GLES2EnsureBackbufferCHROMIUM() {
+  gles2::GetGLContext()->EnsureBackbufferCHROMIUM();
+}
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_C_LIB_AUTOGEN_H_