Rename isolated_output to test_output and add a method to get the test_output directory.

webrtc/test/testsupport/test_output.h

 /*
  *  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.
  */
 
-#ifndef WEBRTC_TEST_TESTSUPPORT_ISOLATED_OUTPUT_H_
-#define WEBRTC_TEST_TESTSUPPORT_ISOLATED_OUTPUT_H_
+#ifndef WEBRTC_TEST_TESTSUPPORT_TEST_OUTPUT_H_
+#define WEBRTC_TEST_TESTSUPPORT_TEST_OUTPUT_H_
 
 #include <stdlib.h>
 
 #include <string>
 
 namespace webrtc {
 namespace test {
 
+// If the test_output_dir flag is set, returns true and copies the location of
+// the dir to |out_dir|. Otherwise, return false.
+bool GetTestOutputDir(std::string* out_dir);
+
 // Writes a |length| bytes array |buffer| to |filename| in isolated output
 // directory defined by swarming. If the file is existing, content will be
 // appended. Otherwise a new file will be created. This function returns false
 // if isolated output directory has not been defined, or |filename| indicates an
 // invalid or non-writable file, or underlying file system errors.
-bool WriteIsolatedOutput(const char* filename,
-                         const uint8_t* buffer,
-                         size_t length);
+bool WriteToTestOutput(const char* filename,
+                       const uint8_t* buffer,
+                       size_t length);
 
-bool WriteIsolatedOutput(const char* filename, const std::string& content);
+bool WriteToTestOutput(const char* filename, const std::string& content);
 
 }  // namespace test
 }  // namespace webrtc
 
-#endif  // WEBRTC_TEST_TESTSUPPORT_ISOLATED_OUTPUT_H_
+#endif  // WEBRTC_TEST_TESTSUPPORT_TEST_OUTPUT_H_