Add CreatePlatformGLTestContext_none.cpp for Google3 build

tools/gpu/gl/none/CreatePlatformGLTestContext_none.cpp

 
 /*
- * Copyright 2012 Google Inc.
+ * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
-#ifndef DebugGLContext_DEFINED
-#define DebugGLContext_DEFINED
 
 #include "gl/GLTestContext.h"
 
 namespace sk_gpu_test {
-GLTestContext* CreateDebugGLTestContext();
+GLTestContext* CreatePlatformGLTestContext(GrGLStandard forcedGpuAPI,
+                                           GLTestContext *shareContext) {
+    return nullptr;
+}
 }  // namespace sk_gpu_test
 
-#endif