SF: make FlagManager singleton

Test: presubmit
Change-Id: Id16425757e818c4867b76548d21fb33cbb3f72d4
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 48be33c..a36def7 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -702,7 +702,7 @@
 
     mFrameTracer->initialize();
     mFrameTimeline->onBootFinished();
-    getRenderEngine().setEnableTracing(mFlagManager.use_skia_tracing());
+    getRenderEngine().setEnableTracing(FlagManager::getInstance().use_skia_tracing());
 
     // wait patiently for the window manager death
     const String16 name("window");
@@ -731,7 +731,7 @@
 
         readPersistentProperties();
         mPowerAdvisor->onBootFinished();
-        const bool hintSessionEnabled = mFlagManager.use_adpf_cpu_hint();
+        const bool hintSessionEnabled = FlagManager::getInstance().use_adpf_cpu_hint();
         mPowerAdvisor->enablePowerHintSession(hintSessionEnabled);
         const bool hintSessionUsed = mPowerAdvisor->usePowerHintSession();
         ALOGD("Power hint is %s",
@@ -6562,7 +6562,7 @@
     /*
      * Dump flag/property manager state
      */
-    mFlagManager.dump(result);
+    FlagManager::getInstance().dump(result);
 
     result.append(mTimeStats->miniDump());
     result.append("\n");