Fix -Wunused-function warning after https://codereview.chromium.org/1673563002

content/common/gpu/media/video_decode_accelerator_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // The bulk of this file is support code; sorry about that.  Here's an overview
 // to hopefully help readers of this code:
 // - RenderingHelper is charged with interacting with X11/{EGL/GLES2,GLX/GL} or
 //   Win/EGL.
 // - ClientState is an enum for the state of the decode client used by the test.
 // - ClientStateNotification is a barrier abstraction that allows the test code
@@ skipping 1178 matching lines @@
 // - reset_after_frame_num: see GLRenderingVDAClient ctor.
 // - delete_decoder_phase: see GLRenderingVDAClient ctor.
 // - whether to test slow rendering by delaying ReusePictureBuffer().
 // - whether the video frames are rendered as thumbnails.
 class VideoDecodeAcceleratorParamTest
     : public VideoDecodeAcceleratorTest,
       public ::testing::WithParamInterface<
         base::Tuple<int, int, int, ResetPoint, ClientState, bool, bool> > {
 };
 
-// Helper so that gtest failures emit a more readable version of the tuple than
-// its byte representation.
-::std::ostream& operator<<(
-    ::std::ostream& os,
-    const base::Tuple<int, int, int, ResetPoint, ClientState, bool, bool>& t) {
-  return os << base::get<0>(t) << ", " << base::get<1>(t) << ", "
-            << base::get<2>(t) << ", " << base::get<3>(t) << ", "
-            << base::get<4>(t) << ", " << base::get<5>(t) << ", "
-            << base::get<6>(t);
-}
-
 // Wait for |note| to report a state and if it's not |expected_state| then
 // assert |client| has deleted its decoder.
 static void AssertWaitForStateOrDeleted(
     ClientStateNotification<ClientState>* note,
     GLRenderingVDAClient* client,
     ClientState expected_state) {
   ClientState state = note->Wait();
   if (state == expected_state) return;
   ASSERT_TRUE(client->decoder_deleted())
       << "Decoder not deleted but Wait() returned " << state
@@ skipping 434 matching lines @@
   content::VaapiWrapper::PreSandboxInitialization();
 #endif
 
   content::g_env =
       reinterpret_cast<content::VideoDecodeAcceleratorTestEnvironment*>(
           testing::AddGlobalTestEnvironment(
               new content::VideoDecodeAcceleratorTestEnvironment()));
 
   return RUN_ALL_TESTS();
 }