TimeCheck: check audio_mutex activity

Add mutex wait chain information and callstacks
to TimeCheck log.

Test: induced wait in PlaybackThread
Bug: 309479717
Change-Id: I4b93b31b23dc13af0d386bc19bb2fcc329b8d2f6
diff --git a/media/utils/TimeCheck.cpp b/media/utils/TimeCheck.cpp
index a5378e6..ec68de7 100644
--- a/media/utils/TimeCheck.cpp
+++ b/media/utils/TimeCheck.cpp
@@ -287,6 +287,11 @@
             .append(halPids).append("\n")
             .append(snapshotAnalysis.toString());
 
+    // In many cases, the initial timeout stack differs from the abort backtrace because
+    // (1) the time difference between initial timeout and the final abort signal
+    // and (2) signalling the HAL audio service may cause
+    // the thread to unblock and continue.
+
     // Note: LOG_ALWAYS_FATAL limits the size of the string - per log/log.h:
     // Log message text may be truncated to less than an
     // implementation-specific limit (1023 bytes).