Fix getUserMedia so that failure is reported for invalid audio sources.

content/shell/renderer/layout_test/blink_test_runner.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/shell/renderer/layout_test/blink_test_runner.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <clocale>
@@ skipping 190 matching lines @@
   }
   void StopCapture() override {}
 };
 
 class MockAudioCapturerSource : public media::AudioCapturerSource {
  public:
   MockAudioCapturerSource() = default;
 
   void Initialize(const media::AudioParameters& params,
                   CaptureCallback* callback,
-                  int session_id) override {}
-  void Start() override {}
+                  int session_id) override {
+    callback_ = callback;
+  }
+  void Start() override {
+    if (callback_)
+      callback_->OnCaptureStarted();
+  }
   void Stop() override {}
   void SetVolume(double volume) override {}
   void SetAutomaticGainControl(bool enable) override {}
 
  protected:
   ~MockAudioCapturerSource() override {}
+
+ private:
+  CaptureCallback* callback_ = nullptr;
+
+  DISALLOW_COPY_AND_ASSIGN(MockAudioCapturerSource);
 };
 
 // Tests in web-platform-tests use absolute path links such as
 //   <script src="/resources/testharness.js">.
 // Because we load the tests as local files, such links don't work.
 // This function fixes this issue by rewriting file: URLs which were produced
 // from such links so that they point actual files in wpt/.
 WebURL RewriteAbsolutePathInWPT(const std::string& utf8_url) {
   const char kFileScheme[] = "file:///";
   const int kFileSchemeLen = arraysize(kFileScheme) - 1;
@@ skipping 802 matching lines @@
 void BlinkTestRunner::ReportLeakDetectionResult(
     const LeakDetectionResult& report) {
   Send(new ShellViewHostMsg_LeakDetectionDone(routing_id(), report));
 }
 
 void BlinkTestRunner::OnDestruct() {
   delete this;
 }
 
 }  // namespace content