Add ability to active multiple devices via the audio API.

chrome/browser/extensions/api/audio/audio_service_chromeos.cc

Index: chrome/browser/extensions/api/audio/audio_service_chromeos.cc
diff --git a/chrome/browser/extensions/api/audio/audio_service_chromeos.cc b/chrome/browser/extensions/api/audio/audio_service_chromeos.cc
index 91a0cd8880425ad149e50d1e4af9b8d7ae3ca256..51039118f5e2fbd0ee93d2e2fe97ce3ac0920e1c 100644
--- a/chrome/browser/extensions/api/audio/audio_service_chromeos.cc
+++ b/chrome/browser/extensions/api/audio/audio_service_chromeos.cc
@@ -9,6 +9,8 @@
 #include "base/strings/string_number_conversions.h"
 #include "chromeos/audio/audio_device.h"
 #include "chromeos/audio/cras_audio_handler.h"
+#include "chromeos/dbus/cras_audio_client.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
@@ -138,6 +140,7 @@ void AudioServiceImpl::SetActiveDevices(const DeviceIdList& device_list) {
   bool input_device_set = false;
   bool output_device_set = false;
 
+  std::string active_input_node_ids, active_output_node_ids;
   for (size_t i = 0; i < device_list.size(); ++i) {
     chromeos::AudioDevice device;
     bool found = FindDevice(GetIdFromStr(device_list[i]), &device);
@@ -145,12 +148,29 @@ void AudioServiceImpl::SetActiveDevices(const DeviceIdList& device_list) {
       if (device.is_input && !input_device_set) {
         cras_audio_handler_->SwitchToDevice(device);
         input_device_set = true;
+        active_input_node_ids.push_back(device.id);

[jennyz, 2014/08/12 18:37:54]

Yes, hychao's comment later is right, this line should be out of the
!input_device_set if block, otherwise active_input_node_ids and
active_output_ids will only contain the first input/output node from
|device_list|. Also, for additional active input/output nodes list, it doesn't
need to include the one that is already set active by SetActiveOutput/InputNode,
right? And you also need to remove the previous active input/output nodes,
otherwise, they may stay active.

       } else if (!device.is_input && !output_device_set) {
         cras_audio_handler_->SwitchToDevice(device);
         output_device_set = true;
+        active_output_node_ids.push_back(device.id);

[hychao, 2014/08/12 10:47:40]

The push_back calls should be pulled out from if/else clause, or there'll  be at
most one device.id push into active_input/output_node_ids.

       }
     }
   }
+
+  // Once we have set our devices to active and all the inactive ones have been
+  // set correctly to inactive, go through our active devices again and set

[hychao, 2014/08/12 10:47:40]

I don't see where we deactivate the old active input/output devs( through
RemoveActiveInputNode). The SwitchToDevice() call above only switches the first
active device, the rest of the previous active devices cause stay active
forever.

+  // them to active using the AddActiveNode API. This is an ugly hack till
+  // http://crbug.com/402072 is fixed.
+  for (size_t i = 0; i < active_input_node_ids.size(); ++i) {
+    chromeos::DBusThreadManager::Get()
+        ->GetCrasAudioClient()
+        ->AddActiveInputNode(active_input_node_ids[i]);
+  }
+  for (size_t i = 0; i < active_output_node_ids.size(); ++i) {
+    chromeos::DBusThreadManager::Get()
+        ->GetCrasAudioClient()
+        ->AddActiveOutputNode(active_output_node_ids[i]);
+  }
 }
 
 bool AudioServiceImpl::SetDeviceProperties(const std::string& device_id,