Fix clang-tidy warnings in audio and playerservice.

* Add explicit keyword to conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
Test: build with WITH_TIDY=1

Change-Id: I265f3b094e08d5705b506b3fbba51439c134af84
Merged-In: I265f3b094e08d5705b506b3fbba51439c134af84
diff --git a/services/audioflinger/Effects.cpp b/services/audioflinger/Effects.cpp
index 949c91d..9d83a7b 100644
--- a/services/audioflinger/Effects.cpp
+++ b/services/audioflinger/Effects.cpp
@@ -1416,7 +1416,7 @@
 }
 
 // Must be called with EffectChain::mLock locked
-void AudioFlinger::EffectChain::clearInputBuffer_l(sp<ThreadBase> thread)
+void AudioFlinger::EffectChain::clearInputBuffer_l(const sp<ThreadBase>& thread)
 {
     // TODO: This will change in the future, depending on multichannel
     // and sample format changes for effects.