AIDL effect: add draining state support

 - effects can transit to DRAINING state with STOP command and continue
   the fade out processing
 - add draining in the audio eraser effect as an example
 - update VTS to support draining

Flag: EXEMPT bugfix
Bug: 379776482
Test: --test-mapping hardware/interfaces/audio/aidl/vts:presubmit

Change-Id: I2ca25cd085d1b6ae6cf8b0d1b58cd713aef0f7e5
diff --git a/audio/aidl/default/EffectImpl.cpp b/audio/aidl/default/EffectImpl.cpp
index 3e61335..7857f53 100644
--- a/audio/aidl/default/EffectImpl.cpp
+++ b/audio/aidl/default/EffectImpl.cpp
@@ -79,7 +79,6 @@
     std::lock_guard lg(mImplMutex);
     RETURN_IF(mState == State::INIT, EX_ILLEGAL_STATE, "alreadyClosed");
 
-    // TODO: b/302036943 add reopen implementation
     RETURN_IF(!mImplContext, EX_NULL_POINTER, "nullContext");
     mImplContext->dupeFmqWithReopen(ret);
     return ndk::ScopedAStatus::ok();
@@ -347,7 +346,7 @@
 
     {
         std::lock_guard lg(mImplMutex);
-        if (mState != State::PROCESSING) {
+        if (mState != State::PROCESSING && mState != State::DRAINING) {
             LOG(DEBUG) << getEffectNameWithVersion()
                        << " skip process in state: " << toString(mState);
             return;