Switching AudioOutputAuthorizationHandler from using AudioManager interface to AudioSystem one.

BUG=672468
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2692203003
Cr-Commit-Position: refs/heads/master@{#450939}
  std::string GetRawNondefaultId() {
    std::string id;
    BrowserThread::PostTask(
        BrowserThread::IO, FROM_HERE,
        base::Bind(
            &AudioOutputAuthorizationHandlerTest::GetRawNondefaultIdOnIOThread,
            base::Unretained(this), base::Unretained(&id)));
    SyncWithAllThreads();
    return id;
  }

  std::string GetRawNondefaultId() {
    std::string id;
    BrowserThread::PostTask(
        BrowserThread::IO, FROM_HERE,
        base::Bind(
            &AudioOutputAuthorizationHandlerTest::GetRawNondefaultIdOnIOThread,
            base::Unretained(this), base::Unretained(&id)));
    SyncWithAllThreads();
    return id;
  }
