audio policy: session routes continued.

- Clear session routes when client process dies.
- Enforce the route only when the requesting session is active.
- Fix requested route not working if an output mix change is required
(e.g forcing to SPEAKER when the default route is USB or A2DP).
- Make sure all sessions sharing the strategy with a rerouted session
have the same route (needed for volume control consistency)

Change-Id: I0ab347a8fb97e73e2c5965374544c5f4fe509ef1
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 8555983..6ea09de 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -1063,7 +1063,7 @@
 
     status_t status;
     status = AudioSystem::getOutputForAttr(attr, &output,
-                                           (audio_session_t)mSessionId, &streamType,
+                                           (audio_session_t)mSessionId, &streamType, mClientUid,
                                            mSampleRate, mFormat, mChannelMask,
                                            mFlags, mSelectedDeviceId, mOffloadInfo);