Replace gflags usages with rtc_base/flags in all targets based on test_main

webrtc/test/testsupport/test_output_unittest.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/test/testsupport/test_output.h"
 
 #include <string.h>
 
 #include <string>
 
-#include "gflags/gflags.h"
 #include "webrtc/rtc_base/file.h"
+#include "webrtc/rtc_base/flags.h"
 #include "webrtc/rtc_base/pathutils.h"
 #include "webrtc/rtc_base/platform_file.h"
 #include "webrtc/test/gtest.h"
 
 DECLARE_string(test_output_dir);
 
 namespace webrtc {
 namespace test {
 
 TEST(IsolatedOutputTest, ShouldRejectInvalidIsolatedOutDir) {
-  std::string backup = FLAGS_test_output_dir;
-  FLAGS_test_output_dir = "";
+  const char* backup = FLAG_test_output_dir;
+  FLAG_test_output_dir = "";
   ASSERT_FALSE(WriteToTestOutput("a-file", "some-contents"));
-  FLAGS_test_output_dir = backup;
+  FLAG_test_output_dir = backup;
 }
 
 TEST(IsolatedOutputTest, ShouldRejectInvalidFileName) {
   ASSERT_FALSE(WriteToTestOutput(nullptr, "some-contents"));
   ASSERT_FALSE(WriteToTestOutput("", "some-contents"));
 }
 
 // Sets isolated_out_dir=<a-writable-path> to execute this test.
 TEST(IsolatedOutputTest, ShouldBeAbleToWriteContent) {
   const char* filename = "a-file";
   const char* content = "some-contents";
   if (WriteToTestOutput(filename, content)) {
-    rtc::Pathname out_file(FLAGS_test_output_dir, filename);
+    rtc::Pathname out_file(FLAG_test_output_dir, filename);
     rtc::File input = rtc::File::Open(out_file);
     EXPECT_TRUE(input.IsOpen());
     EXPECT_TRUE(input.Seek(0));
     uint8_t buffer[32];
     EXPECT_EQ(input.Read(buffer, strlen(content)), strlen(content));
     buffer[strlen(content)] = 0;
     EXPECT_EQ(std::string(content),
               std::string(reinterpret_cast<char*>(buffer)));
     input.Close();
 
     EXPECT_TRUE(rtc::File::Remove(out_file));
   }
 }
 
 }  // namespace test
 }  // namespace webrtc