Add CreatePlatformGLTestContext_none.cpp for Google3 build

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1847923002

Review URL: https://codereview.chromium.org/1847923002

gyp/gputest.gyp

@@ -85,6 +85,9 @@
             ],
           },
         }],
+        ['skia_os in ["linux", "win", "mac", "chromeos", "android", "ios"]', {
+          'sources/': [ ['exclude', '_none\.(h|cpp)$'],],
+        }],
         ['skia_os != "win"', {
           'sources/': [ ['exclude', '_win\.(h|cpp)$'],],
         }],

tools/gpu/gl/none/CreatePlatformGLTestContext_none.cpp

@@ -0,0 +1,17 @@
+
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gl/GLTestContext.h"
+
+namespace sk_gpu_test {
+GLTestContext* CreatePlatformGLTestContext(GrGLStandard forcedGpuAPI,
+                                           GLTestContext *shareContext) {
+    return nullptr;
+}
+}  // namespace sk_gpu_test
+