Properly set loopback device ID for system audio capture.

chrome/browser/media/media_capture_devices_dispatcher.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 "chrome/browser/media/media_capture_devices_dispatcher.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/prefs/pref_service.h"
 #include "base/sha1.h"
@@ skipping 17 matching lines @@
 #include "content/public/browser/media_devices_monitor.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/media_stream_request.h"
 #include "extensions/common/constants.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(USE_CRAS)
+#include "media/audio/cras/audio_manager_cras.h"
+#endif
+
 using content::BrowserThread;
 using content::MediaStreamDevices;
 
 namespace {
 
 // Finds a device in |devices| that has |device_id|, or NULL if not found.
 const content::MediaStreamDevice* FindDeviceWithId(
     const content::MediaStreamDevices& devices,
     const std::string& device_id) {
   content::MediaStreamDevices::const_iterator iter = devices.begin();
@@ skipping 138 matching lines @@
   } else {
     ProcessRegularMediaAccessRequest(web_contents, request, callback);
   }
 }
 
 void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
     content::WebContents* web_contents,
     const content::MediaStreamRequest& request,
     const content::MediaResponseCallback& callback,
     const extensions::Extension* extension) {
-  bool component_extension =
+  const bool component_extension =
     extension && extension->location() == extensions::Manifest::COMPONENT;
 
   content::MediaStreamDevices devices;
 
-  bool screen_capture_enabled =
+  const bool screen_capture_enabled =
       CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableUserMediaScreenCapturing) ||
       IsOriginWhitelistedForScreenCapture(request.security_origin);
 
-  bool origin_is_secure =
+  const bool origin_is_secure =
       request.security_origin.SchemeIsSecure() ||
       request.security_origin.SchemeIs(extensions::kExtensionScheme) ||
       CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kAllowHttpScreenCapture);
 
+  const bool screen_video_capture_requested =
+      request.video_type == content::MEDIA_SCREEN_VIDEO_CAPTURE;
+
+  const bool system_audio_capture_requested =
+      request.audio_type == content::MEDIA_SYSTEM_AUDIO_CAPTURE;
+
+#if defined(USE_CRAS)
+  const bool system_audio_capture_supported = true;
+#else
+  const bool system_audio_capture_supported = false;
+#endif
+
   // Approve request only when the following conditions are met:
   //  1. Screen capturing is enabled via command line switch or white-listed for
   //     the given origin.
   //  2. Request comes from a page with a secure origin or from an extension.
   //  3. Video capture is requested for screen video.
   //  4. Audio capture is either not requested, or requested for system audio.
   if (screen_capture_enabled && origin_is_secure &&
-      request.video_type == content::MEDIA_SCREEN_VIDEO_CAPTURE &&
-      (request.audio_type == content::MEDIA_NO_SERVICE ||
-       request.audio_type == content::MEDIA_SYSTEM_AUDIO_CAPTURE)) {
+      screen_video_capture_requested &&
+      (!system_audio_capture_requested || system_audio_capture_supported)) {
     // For component extensions, bypass message box.
     bool user_approved = false;
     if (!component_extension) {
       string16 application_name = UTF8ToUTF16(request.security_origin.spec());
       string16 confirmation_text = l10n_util::GetStringFUTF16(
           request.audio_type == content::MEDIA_NO_SERVICE ?
               IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TEXT :
               IDS_MEDIA_SCREEN_AND_AUDIO_CAPTURE_CONFIRMATION_TEXT,
           application_name);
       chrome::MessageBoxResult result = chrome::ShowMessageBox(
           NULL,
           l10n_util::GetStringFUTF16(
               IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TITLE, application_name),
           confirmation_text,
           chrome::MESSAGE_BOX_TYPE_QUESTION);
       user_approved = (result == chrome::MESSAGE_BOX_RESULT_YES);
     }
 
     if (user_approved || component_extension) {
       devices.push_back(content::MediaStreamDevice(
           content::MEDIA_SCREEN_VIDEO_CAPTURE, std::string(), "Screen"));
-      if (request.audio_type == content::MEDIA_SYSTEM_AUDIO_CAPTURE) {
+      if (system_audio_capture_requested) {
+#if defined(USE_CRAS)
+        // Use the special loopback device ID for system audio capture.
         devices.push_back(content::MediaStreamDevice(
-            content::MEDIA_SYSTEM_AUDIO_CAPTURE, std::string(), std::string()));
+            content::MEDIA_SYSTEM_AUDIO_CAPTURE,
+            media::AudioManagerCras::kLoopbackDeviceId,
+            "System Audio"));
+#endif
       }
     }
   }
 
   scoped_ptr<content::MediaStreamUI> ui;
   // Unless we're being invoked from a component extension, register to display
   // the notification for stream capture.
   if (!devices.empty() && !component_extension) {
     // Use extension name as title for extensions and origin for drive-by web.
     std::string title;
@@ skipping 313 matching lines @@
                                     state));
 }
 
 void MediaCaptureDevicesDispatcher::OnCreatingAudioStreamOnUIThread(
     int render_process_id,
     int render_view_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   FOR_EACH_OBSERVER(Observer, observers_,
                     OnCreatingAudioStream(render_process_id, render_view_id));
 }