FastThread: Remove unused NBLog variable

Test: Compile and verify NBLog
Change-Id: I145eb480415b076b7f75d266df35fc945563a364

services/audioflinger/FastThread.cpp

@@ -66,8 +66,6 @@ FastThread::FastThread(const char *cycleMs, const char *loadUs) : Thread(false /
     /* mMeasuredWarmupTs({0, 0}), */
     mWarmupCycles(0),
     mWarmupConsecutiveInRangeCycles(0),
-    mDummyNBLogWriter(new NBLog::Writer()),
-    mNBLogWriter(mDummyNBLogWriter.get()),
     mTimestampStatus(INVALID_OPERATION),
 
     mCommand(FastThreadState::INITIAL),
@@ -124,10 +122,9 @@ bool FastThread::threadLoop()
 
             // As soon as possible of learning of a new dump area, start using it
             mDumpState = next->mDumpState != NULL ? next->mDumpState : mDummyDumpState;
-            mNBLogWriter = next->mNBLogWriter != NULL ?
+            tlNBLogWriter = next->mNBLogWriter != NULL ?
                     next->mNBLogWriter : mDummyNBLogWriter.get();
-            setNBLogWriter(mNBLogWriter);   // FastMixer informs its AudioMixer, FastCapture ignores
-            tlNBLogWriter = mNBLogWriter;
+            setNBLogWriter(tlNBLogWriter); // FastMixer informs its AudioMixer, FastCapture ignores
 
             // We want to always have a valid reference to the previous (non-idle) state.
             // However, the state queue only guarantees access to current and previous states.

services/audioflinger/FastThread.h

@@ -81,9 +81,7 @@ protected:
     struct timespec   mMeasuredWarmupTs;  // how long did it take for warmup to complete
     uint32_t          mWarmupCycles;  // counter of number of loop cycles during warmup phase
     uint32_t          mWarmupConsecutiveInRangeCycles;    // number of consecutive cycles in range
-    sp<NBLog::Writer> mDummyNBLogWriter;
-    NBLog::Writer*    mNBLogWriter;   // always non-nullptr: real NBLog::Writer* or
-                                      // mDummyNBLogWriter.get()
+    const sp<NBLog::Writer> mDummyNBLogWriter{new NBLog::Writer()};
     status_t          mTimestampStatus;
 
     FastThreadState::Command mCommand;