Add a new audio constraint, 'googHotword', that requests the hotword input

content/browser/renderer_host/media/media_stream_manager.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/browser/renderer_host/media/media_stream_manager.h"
 
 #include <list>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 116 matching lines @@
 void FilterAudioEffects(const StreamOptions& options, int* effects) {
   DCHECK(effects);
   // TODO(ajm): Should we also handle ECHO_CANCELLER here?
   std::string value;
   if (options.GetFirstAudioConstraintByName(
           kMediaStreamAudioDucking, &value, NULL) && value == "false") {
     *effects &= ~media::AudioParameters::DUCKING;
   }
 }
 
+// Unlike other effects, hotword is off by default, so turn it on if it's
+// requested and available.
+void EnableHotwordEffect(const StreamOptions& options, int* effects) {
+  DCHECK(effects);
+  std::string value;
+  if (options.GetFirstAudioConstraintByName(
+          kMediaStreamAudioHotword, &value, NULL) && value == "true") {
+#if defined(OS_CHROMEOS)
+    chromeos::AudioDeviceList devices;
+    chromeos::CrasAudioHandler::Get()->GetAudioDevices(&devices);

[DaleCurtis, 2015/01/05 22:57:52]

Is this something you want to check every time? Device enumeration can be slow.

[Anand Mistry (off Chromium), 2015/01/06 02:02:40]

As far as I can tell, this is a non-blocking operation (just a map iteration).
It should only be an issue if the list of devices is extremely large.

+    // Only enable if a hotword device exists.
+    for (size_t i = 0; i < devices.size(); ++i) {
+      if (devices[i].type == chromeos::AUDIO_TYPE_AOKR) {
+        DCHECK(devices[i].is_input);
+        *effects |= media::AudioParameters::HOTWORD;
+      }
+    }
+#endif
+  }
+}
+
 // Private helper method for SendMessageToNativeLog() that obtains the global
 // MediaStreamManager instance on the UI thread before sending |message| to the
 // webrtcLoggingPrivate API.
 void DoAddLogMessage(const std::string& message) {
   // Must be on the UI thread to access BrowserMainLoop.
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   // May be null in tests.
   // TODO(vrk): Handle this more elegantly by having native log messages become
   // no-ops until MediaStreamManager is aware that a renderer process has
   // started logging. crbug.com/333894
@@ skipping 1258 matching lines @@
       for (StreamDeviceInfoArray::const_iterator device_it =
                request->devices.begin();
            device_it != request->devices.end(); ++device_it) {
         if (device_it->device.id == source_id &&
             device_it->device.type == new_device_info.type) {
           *existing_device_info = *device_it;
           // Make sure that the audio |effects| reflect what the request
           // is set to and not what the capabilities are.
           FilterAudioEffects(request->options,
               &existing_device_info->device.input.effects);
+          EnableHotwordEffect(request->options,
+                              &existing_device_info->device.input.effects);
           *existing_request_state = request->state(device_it->device.type);
           return true;
         }
       }
     }
   }
   return false;
 }
 
 void MediaStreamManager::FinalizeGenerateStream(const std::string& label,
@@ skipping 219 matching lines @@
                 audio_input_device_manager_->GetOpenedDeviceInfoById(
                     device_it->session_id);
             device_it->device.input = info->device.input;
 
             // Since the audio input device manager will set the input
             // parameters to the default settings (including supported effects),
             // we need to adjust those settings here according to what the
             // request asks for.
             FilterAudioEffects(request->options,
                 &device_it->device.input.effects);
+            EnableHotwordEffect(request->options,
+                                &device_it->device.input.effects);
 
             device_it->device.matched_output = info->device.matched_output;
           }
         }
         if (RequestDone(*request))
           HandleRequestDone(label, request);
         break;
       }
     }
   }
@@ skipping 467 matching lines @@
   }
 }
 
 void MediaStreamManager::SetKeyboardMicOnDeviceThread() {
   DCHECK(device_task_runner_->BelongsToCurrentThread());
   audio_manager_->SetHasKeyboardMic();
 }
 #endif
 
 }  // namespace content