Audio effects: define interface between EffectModule and audio framework

This is in preparation of the addition of audio effects attached to a
specific audio device that will not be attached to a particular
ThreadBase or Effectchain.

Create an clean callback interface used by the EffectModule to interact
with the rest of the audio framework. This callback must be implemented
by the EffectModule parent (e.g an EfffectChain).

Als refactor EffectHandle enabled(), disable() and disconnect methods()
to avoid dealing with the ThreadBase directly.

Bug: 136294538
Test: make
Change-Id: I9160f88f7fbb0447b5e679260bf0401d3af591d2
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index ef7eb6e..f1adc23 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -271,6 +271,8 @@
                 // Called by AudioFlinger::frameCount(audio_io_handle_t output) and effects,
                 // and returns the [normal mix] buffer's frame count.
     virtual     size_t      frameCount() const = 0;
+    virtual     uint32_t    latency_l() const { return 0; }
+    virtual     void        setVolumeForOutput_l(float left __unused, float right __unused) const {}
 
                 // Return's the HAL's frame count i.e. fast mixer buffer size.
                 size_t      frameCountHAL() const { return mFrameCount; }
@@ -424,14 +426,9 @@
 
                 // check if some effects must be suspended/restored when an effect is enabled
                 // or disabled
-                void checkSuspendOnEffectEnabled(const sp<EffectModule>& effect,
-                                                 bool enabled,
-                                                 audio_session_t sessionId =
-                                                        AUDIO_SESSION_OUTPUT_MIX);
-                void checkSuspendOnEffectEnabled_l(const sp<EffectModule>& effect,
-                                                   bool enabled,
-                                                   audio_session_t sessionId =
-                                                        AUDIO_SESSION_OUTPUT_MIX);
+                void checkSuspendOnEffectEnabled(bool enabled,
+                                                 audio_session_t sessionId,
+                                                 bool threadLocked);
 
                 virtual status_t    setSyncEvent(const sp<SyncEvent>& event) = 0;
                 virtual bool        isValidSyncEvent(const sp<SyncEvent>& event) const = 0;
@@ -465,6 +462,9 @@
 
     mutable     Mutex                   mLock;
 
+                void onEffectEnable(const sp<EffectModule>& effect);
+                void onEffectDisable();
+
 protected:
 
                 // entry describing an effect being suspended in mSuspendedSessions keyed vector
@@ -814,7 +814,7 @@
                 // return estimated latency in milliseconds, as reported by HAL
                 uint32_t    latency() const;
                 // same, but lock must already be held
-                uint32_t    latency_l() const;
+                uint32_t    latency_l() const override;
 
                 // VolumeInterface
     virtual     void        setMasterVolume(float value);
@@ -824,7 +824,7 @@
     virtual     void        setStreamMute(audio_stream_type_t stream, bool muted);
     virtual     float       streamVolume(audio_stream_type_t stream) const;
 
-                void        setVolumeForOutput_l(float left, float right) const;
+                void        setVolumeForOutput_l(float left, float right) const override;
 
                 sp<Track>   createTrack_l(
                                 const sp<AudioFlinger::Client>& client,