Properly set loopback device ID for system audio capture.

Make sure the MediaStreamDevice has the correct loopback device ID for system
audio capture in MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest.
Remove the hack in audio_input_renderer_host to override the loopback device ID.

BUG=269626
TBR=dalecurtis@chromium.org, xians@chromium.org
TEST=passes trybots, local testing on Chrome OS confirms device ID is passed to WebRtcLocalAudioTrack ctor.

Review URL: https://codereview.chromium.org/22408006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@216271 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 39 insertions, 32 deletions

diff --git a/build/common.gypi b/build/common.gypi
index 29f1278..4b36fdf 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -27,6 +27,9 @@
             # Whether or not we are building the Ash shell.
             'use_ash%': 0,
 
+            # Whether or not we are using CRAS, the ChromeOS Audio Server.
+            'use_cras%': 0,
+
             # Use a raw surface abstraction.
             'use_ozone%': 0,
           },
@@ -34,6 +37,7 @@
           'chromeos%': '<(chromeos)',
           'use_aura%': '<(use_aura)',
           'use_ash%': '<(use_ash)',
+          'use_cras%': '<(use_cras)',
           'use_ozone%': '<(use_ozone)',
 
           # Whether we are using Views Toolkit
@@ -98,6 +102,7 @@
         'chromeos%': '<(chromeos)',
         'use_aura%': '<(use_aura)',
         'use_ash%': '<(use_ash)',
+        'use_cras%': '<(use_cras)',
         'use_ozone%': '<(use_ozone)',
         'use_openssl%': '<(use_openssl)',
         'enable_viewport%': '<(enable_viewport)',
@@ -179,6 +184,7 @@
       'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
       'use_aura%': '<(use_aura)',
       'use_ash%': '<(use_ash)',
+      'use_cras%': '<(use_cras)',
       'use_ozone%': '<(use_ozone)',
       'use_openssl%': '<(use_openssl)',
       'enable_viewport%': '<(enable_viewport)',
@@ -755,6 +761,7 @@
     'ui_compositor_image_transport%': '<(ui_compositor_image_transport)',
     'use_aura%': '<(use_aura)',
     'use_ash%': '<(use_ash)',
+    'use_cras%': '<(use_cras)',
     'use_openssl%': '<(use_openssl)',
     'use_nss%': '<(use_nss)',
     'os_bsd%': '<(os_bsd)',
@@ -1928,6 +1935,9 @@
       ['use_ash==1', {
         'defines': ['USE_ASH=1'],
       }],
+      ['use_cras==1', {
+        'defines': ['USE_CRAS=1'],
+      }],
       ['use_ozone==1', {
         'defines': ['USE_OZONE=1'],
       }],
diff --git a/chrome/browser/media/media_capture_devices_dispatcher.cc b/chrome/browser/media/media_capture_devices_dispatcher.cc
index bbef40f..03ca4c5 100644
--- a/chrome/browser/media/media_capture_devices_dispatcher.cc
+++ b/chrome/browser/media/media_capture_devices_dispatcher.cc
@@ -35,6 +35,10 @@
 #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;
 
@@ -193,22 +197,34 @@ void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
     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.
@@ -216,9 +232,8 @@ void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
   //  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) {
@@ -240,9 +255,14 @@ void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
     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
       }
     }
   }
diff --git a/content/browser/renderer_host/media/audio_input_renderer_host.cc b/content/browser/renderer_host/media/audio_input_renderer_host.cc
index 37d93ef..4a2f731 100644
--- a/content/browser/renderer_host/media/audio_input_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_input_renderer_host.cc
@@ -15,10 +15,6 @@
 #include "content/browser/renderer_host/media/web_contents_capture_util.h"
 #include "media/audio/audio_manager_base.h"
 
-#if defined(USE_CRAS)
-#include "media/audio/cras/audio_manager_cras.h"
-#endif
-
 namespace content {
 
 struct AudioInputRendererHost::AudioEntry {
@@ -241,18 +237,7 @@ void AudioInputRendererHost::OnCreateStream(
       return;
     }
 
-    if (info->device.type == content::MEDIA_SYSTEM_AUDIO_CAPTURE) {
-#if defined(USE_CRAS)
-      // Use the special loopback device ID for system audio capture.
-      device_id = media::AudioManagerCras::kLoopbackDeviceId;
-#else
-      SendErrorMessage(stream_id);
-      DLOG(WARNING) << "Loopback device is not supported on this platform";
-      return;
-#endif
-    } else {
-      device_id = info->device.id;
-    }
+    device_id = info->device.id;
   }
 
   // Create a new AudioEntry structure.
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index 5644323..3f12bd7 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -3,9 +3,6 @@
 # found in the LICENSE file.
 
 {
-  'variables': {
-    'use_cras%': 0,
-  },
   'dependencies': [
     'browser/speech/proto/speech_proto.gyp:speech_proto',
     '../base/base.gyp:base_static',
@@ -1373,11 +1370,6 @@
         '../build/linux/system.gyp:x11',
       ],
     }],
-    ['use_cras==1', {
-      'defines': [
-        'USE_CRAS',
-      ],
-    }],
     ['use_pango==1', {
       'dependencies': [
         '../build/linux/system.gyp:pangocairo',