AudioFlinger: add audio session for device effects

Add specific audio session ID for effects applied to a
particular audio device.
Device specific effects will be attached to a particular audio sink or
source device identified by its unique audio port ID and will all use
this same session ID.
Only one session of this type exists on a given playback or record
thread.
All effects in this session apply to the same device ID and are created/released
when the routing (audio patch) of this thread output or input stream is updated.

Bug: 136294538
Test: make

Change-Id: I4e3a55ed1244b918429dd9e217b6efecc1ec6449
Merged-In: I4e3a55ed1244b918429dd9e217b6efecc1ec6449
diff --git a/services/audioflinger/Effects.cpp b/services/audioflinger/Effects.cpp
index bbd0d2c..6e36a01 100644
--- a/services/audioflinger/Effects.cpp
+++ b/services/audioflinger/Effects.cpp
@@ -637,7 +637,7 @@
     mConfig.outputCfg.bufferProvider.releaseBuffer = NULL;
     mConfig.inputCfg.accessMode = EFFECT_BUFFER_ACCESS_READ;
     // Insert effect:
-    // - in session AUDIO_SESSION_OUTPUT_MIX or AUDIO_SESSION_OUTPUT_STAGE,
+    // - in global sessions (e.g AUDIO_SESSION_OUTPUT_MIX),
     // always overwrites output buffer: input buffer == output buffer
     // - in other sessions:
     //      last effect in the chain accumulates in output buffer: input buffer != output buffer
@@ -2063,14 +2063,12 @@
         ALOGW("process_l(): cannot promote mixer thread");
         return;
     }
-    bool isGlobalSession = (mSessionId == AUDIO_SESSION_OUTPUT_MIX) ||
-            (mSessionId == AUDIO_SESSION_OUTPUT_STAGE);
     // never process effects when:
     // - on an OFFLOAD thread
     // - no more tracks are on the session and the effect tail has been rendered
     bool doProcess = (thread->type() != ThreadBase::OFFLOAD)
                   && (thread->type() != ThreadBase::MMAP);
-    if (!isGlobalSession) {
+    if (!audio_is_global_session(mSessionId)) {
         bool tracksOnSession = (trackCnt() != 0);
 
         if (!tracksOnSession && mTailBufferCount == 0) {