audio: fix stream type for accessibility usage

Make sure that accessibility prompts are heard when
a ringtone is active by forcing stream type
to AUDIO_STREAM_RING when phone state is AUDIO_MODE_RINGTONE.

Bug: 17558149.
Change-Id: Ia3bead8052fca5cbf282c267f7b9b06014fef628
diff --git a/services/audiopolicy/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
index 2c51e25..b212ca6 100644
--- a/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
@@ -80,9 +80,16 @@
 
     Mutex::Autolock _l(mLock);
     mAudioPolicyManager->setPhoneState(state);
+    mPhoneState = state;
     return NO_ERROR;
 }
 
+audio_mode_t AudioPolicyService::getPhoneState()
+{
+    Mutex::Autolock _l(mLock);
+    return mPhoneState;
+}
+
 status_t AudioPolicyService::setForceUse(audio_policy_force_use_t usage,
                                          audio_policy_forced_cfg_t config)
 {