Collapse most spammy output of webrtc_perf_tests with PrintResultList

webrtc/test/testsupport/perf_test.h

 /*
  *  Copyright (c) 2012 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.
  */
 
 // A stripped-down version of Chromium's chrome/test/perf/perf_test.h.
 // Several functions have been removed; the prototypes of the remainder have
 // not been changed.
 
 #ifndef WEBRTC_TEST_TESTSUPPORT_PERF_TEST_H_
 #define WEBRTC_TEST_TESTSUPPORT_PERF_TEST_H_
 
+#include <sstream>
 #include <string>
 
 namespace webrtc {
 namespace test {
 
 // Prints numerical information to stdout in a controlled format, for
 // post-processing. |measurement| is a description of the quantity being
 // measured, e.g. "vm_peak"; |modifier| is provided as a convenience and
 // will be appended directly to the name of the |measurement|, e.g.
 // "_browser"; |trace| is a description of the particular data point, e.g.
@@ skipping 81 matching lines @@
 
 void PrintSystemCommitCharge(FILE* target,
                              const std::string& test_name,
                              size_t charge,
                              bool important);
 
 std::string SystemCommitChargeToString(const std::string& test_name,
                                        size_t charge,
                                        bool important);
 
+// Converts list of values into comma-separated string for PrintResultList.
+template <typename Container>
+std::string ValuesToString(const Container& container) {
+  if (container.empty())
+    return "";
+
+  std::stringstream ss;
+  auto it = container.begin();
+  while (true) {
+    ss << *it;
+    if (++it == container.end())
+      break;
+    ss << ',';
+  }
+  return ss.str();
+}
+
 }  // namespace test
 }  // namespace webrtc
 
 #endif  // WEBRTC_TEST_TESTSUPPORT_PERF_TEST_H_