logd: don't use a thread for deleting log chunks

This was a premature optimization.  Profiling shows that decompressing
and deleting these logs is rather fast and overall CPU utilization is
lower without the added thread.

Test: profile logd with/without this thread
Change-Id: I31bd52077b495d562dd5797585191dc200ad3859
diff --git a/logd/SerializedLogBuffer.h b/logd/SerializedLogBuffer.h
index 2b2559f..a03050e 100644
--- a/logd/SerializedLogBuffer.h
+++ b/logd/SerializedLogBuffer.h
@@ -37,7 +37,6 @@
 class SerializedLogBuffer final : public LogBuffer {
   public:
     SerializedLogBuffer(LogReaderList* reader_list, LogTags* tags, LogStatistics* stats);
-    ~SerializedLogBuffer();
     void Init() override;
 
     int Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid, const char* msg,
@@ -61,11 +60,9 @@
             REQUIRES_SHARED(lock_);
     void NotifyReadersOfPrune(log_id_t log_id, const std::list<SerializedLogChunk>::iterator& chunk)
             REQUIRES(reader_list_->reader_threads_lock());
+    void RemoveChunkFromStats(log_id_t log_id, SerializedLogChunk& chunk);
     unsigned long GetSizeUsed(log_id_t id) REQUIRES(lock_);
 
-    void StartDeleterThread() REQUIRES(lock_);
-    void DeleterThread();
-
     LogReaderList* reader_list_;
     LogTags* tags_;
     LogStatistics* stats_;
@@ -74,9 +71,5 @@
     std::list<SerializedLogChunk> logs_[LOG_ID_MAX] GUARDED_BY(lock_);
     RwLock lock_;
 
-    std::list<SerializedLogChunk> chunks_to_delete_[LOG_ID_MAX] GUARDED_BY(lock_);
-    std::thread deleter_thread_ GUARDED_BY(lock_);
-    bool deleter_thread_running_ GUARDED_BY(lock_) = false;
-
     std::atomic<uint64_t> sequence_ = 1;
 };