Add GL_CHROMIUM_map_sub functions to GrGLInterface and bit to GrGLCaps.

src/gpu/gl/GrGLInterface.cpp

Index: src/gpu/gl/GrGLInterface.cpp
diff --git a/src/gpu/gl/GrGLInterface.cpp b/src/gpu/gl/GrGLInterface.cpp
index c5ab39ac7b55d1c6b6951d172f883aeb57287a64..bfffdfb192a55b9749122203e3340ce2d22d783b 100644
--- a/src/gpu/gl/GrGLInterface.cpp
+++ b/src/gpu/gl/GrGLInterface.cpp
@@ -504,6 +504,15 @@ bool GrGLInterface::validate() const {
             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;