Persist the user's active audio device choice across chromeos session and reboots.

This cl added a new attribute to device's active state settings to describe if the device is made active by user's selection or by automatic priority selection. The device made active by user has a higher priority than the device made active by priority.

With the stable device id, the active device selection rule is different than before, which only select the active device by its priority. Please see the details in the following document.
https://docs.google.com/a/google.com/document/d/1zmSeM956Njh_9ZdLqyld-NTOpJyXVIfzv8DvQ1Xcksw/edit?usp=sharing

BUG=308143
TBR=stevenjb,rkc,derat

Review URL: https://codereview.chromium.org/1746843002

Cr-Commit-Position: refs/heads/master@{#378812}

1 files changed, 5 insertions, 0 deletions

diff --git a/chromeos/dbus/fake_cras_audio_client.cc b/chromeos/dbus/fake_cras_audio_client.cc
index 8bffa16..b8778ca 100644
--- a/chromeos/dbus/fake_cras_audio_client.cc
+++ b/chromeos/dbus/fake_cras_audio_client.cc
@@ -174,6 +174,11 @@ void FakeCrasAudioClient::AddActiveOutputNode(uint64_t node_id) {
   }
 }
 
+void FakeCrasAudioClient::WaitForServiceToBeAvailable(
+    const WaitForServiceToBeAvailableCallback& callback) {
+  callback.Run(true);
+}
+
 void FakeCrasAudioClient::RemoveActiveOutputNode(uint64_t node_id) {
   for (size_t i = 0; i < node_list_.size(); ++i) {
     if (node_list_[i].id == node_id)