Add a default implementation in metrics_default.cc of histograms methods in system_wrappers/interfac

webrtc/api/api_tests.gyp

 # Copyright (c) 2015 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.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 82 matching lines @@
         }],
         ['OS=="android"', {
           'sources': [
             'test/androidtestinitializer.cc',
             'test/androidtestinitializer.h',
           ],
           'dependencies': [
             '<(DEPTH)/testing/android/native_test.gyp:native_test_native_code',
             '<(webrtc_root)/api/api.gyp:libjingle_peerconnection_jni',
           ],
+        }, {
+          'dependencies': [
+            '<(webrtc_root)/system_wrappers/system_wrappers.gyp:metrics_default',
+          ],
         }],
         ['OS=="win" and clang==1', {
           'msvs_settings': {
             'VCCLCompilerTool': {
               'AdditionalOptions': [
                 # Disable warnings failing when compiling with Clang on Windows.
                 # https://bugs.chromium.org/p/webrtc/issues/detail?id=5366
                 '-Wno-sign-compare',
                 '-Wno-unused-function',
               ],
@@ skipping 73 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'peerconnection_unittests.isolate',
           ],
         },
       ],  # targets
     }],  # test_isolation_mode != "noop"
   ],  # conditions
 }