Use local pages for webrtc telemetry tests.

tools/perf/page_sets/webrtc_cases/peerconnection_audio_files/main(1).css

+/*
+ *  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.
+ */
+audio {
+  display: inline-block;
+  position: relative;
+  top: 9px;
+  width: calc(100% - 120px);
+}
+
+button {
+  margin: 0 20px 0 0;
+  width: 96px;
+}
+
+div#audio {
+  margin: 0 0 29px 0;
+}
+
+div#audio > div {
+  margin: 0 0 20px 0;
+}
+
+div.label {
+  display: inline-block;
+  font-weight: 400;
+  width: 120px;
+}
+
+div.graph-container {
+  float: left;
+  margin: 0.5em;
+  width: calc(50% - 1em);
+}
+
+a#viewSource {
+  clear: both;
+}