media log: do not lock mutex in dump()

Just try locking the mutex when dumping media.log service
and continue in case of failure.

Bug: 27408518
Change-Id: Ib24e5fcd6b7365ab04fb145f704cecfa0f6b70e5
diff --git a/services/medialog/MediaLogService.h b/services/medialog/MediaLogService.h
index 2d89a41..c9bf2eb 100644
--- a/services/medialog/MediaLogService.h
+++ b/services/medialog/MediaLogService.h
@@ -43,6 +43,12 @@
                                 uint32_t flags);
 
 private:
+
+    // Internal dump
+    static const int kDumpLockRetries = 50;
+    static const int kDumpLockSleepUs = 20000;
+    static bool dumpTryLock(Mutex& mutex);
+
     Mutex               mLock;
     class NamedReader {
     public: