Add GL_CHROMIUM_map_sub functions to GrGLInterface and bit to GrGLCaps.

src/gpu/gl/GrGLInterface.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "gl/GrGLInterface.h"
 #include "gl/GrGLExtensions.h"
@@ skipping 486 matching lines @@
             NULL == fFunctions.fInvalidateTexSubImage) {
             RETURN_FALSE_INTERFACE;
         }
     } else if (glVer >= GR_GL_VER(3,0)) {
         // ES 3.0 adds the framebuffer functions but not the others.
         if (NULL == fFunctions.fInvalidateFramebuffer ||
             NULL == fFunctions.fInvalidateSubFramebuffer) {
             RETURN_FALSE_INTERFACE;
         }
     }
+
+    if (kGLES_GrGLStandard == fStandard && fExtensions.has("GL_CHROMIUM_map_sub")) {
+        if (NULL == fFunctions.fMapBufferSubData ||
+            NULL == fFunctions.fMapTexSubImage2D ||
+            NULL == fFunctions.fUnmapBufferSubData ||
+            NULL == fFunctions.fUnmapTexSubImage2D) {
+            RETURN_FALSE_INTERFACE;
+        }
+    }
 #endif
 
     return true;
 }