Reland of Use spec-compliant algorithm to select video devices in getUserMedia.

extensions/browser/guest_view/app_view/app_view_apitest.cc

 // Copyright 2014 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 "base/command_line.h"
 #include "base/path_service.h"
 #include "base/strings/stringprintf.h"
 #include "components/guest_view/browser/guest_view_manager.h"
 #include "components/guest_view/browser/guest_view_manager_factory.h"
 #include "components/guest_view/browser/test_guest_view_manager.h"
@@ skipping 128 matching lines @@
         content::ExecuteScript(embedder_web_contents_,
                                base::StringPrintf("runTest('%s', '%s')",
                                                   test_name.c_str(),
                                                   app_embedded->id().c_str())))
         << "Unable to start test.";
     ASSERT_TRUE(done_listener.WaitUntilSatisfied());
   }
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     AppShellTest::SetUpCommandLine(command_line);
+    // This switch ensures that there will always be at least one media device,
+    // even on machines without physical devices. This is required by tests that
+    // request permission to use media devices.
+    command_line->AppendSwitch("use-fake-device-for-media-stream");
 
     bool use_cross_process_frames_for_guests = GetParam();
     if (use_cross_process_frames_for_guests) {
       command_line->AppendSwitchASCII(
           switches::kEnableFeatures,
           ::features::kGuestViewCrossProcessFrames.name);
     } else {
       command_line->AppendSwitchASCII(
           switches::kDisableFeatures,
           ::features::kGuestViewCrossProcessFrames.name);
@@ skipping 50 matching lines @@
 #endif
 // Tests that <appview> is able to navigate to another installed app.
 IN_PROC_BROWSER_TEST_P(AppViewTest,
                        MAYBE_TestAppViewWithUndefinedDataShouldSucceed) {
   RunTest("testAppViewWithUndefinedDataShouldSucceed",
           "app_view/apitest",
           "app_view/apitest/skeleton");
 }
 
 }  // namespace extensions