Preload zip before waiting for surface flinger

This saves about 200 msec by preloading media zip file before waiting
for surface flinger becomes ready.

Android Auto results:
BootAnimation: BootAnimationPreloadTiming start time: 8261ms
BootAnimation: BootAnimationPreloadStopTiming start time: 8508ms

Bug: 62056504

Test: adb logcat -s BootAnimation
Change-Id: Iaedf774983a66c2838452c45a04b3a1f4c728f17
diff --git a/cmds/bootanimation/BootAnimation.h b/cmds/bootanimation/BootAnimation.h
index 19616cb..dc19fb0 100644
--- a/cmds/bootanimation/BootAnimation.h
+++ b/cmds/bootanimation/BootAnimation.h
@@ -115,6 +115,7 @@
     };
 
     explicit BootAnimation(sp<Callbacks> callbacks);
+    virtual ~BootAnimation();
 
     sp<SurfaceComposerClient> session() const;
 
@@ -155,6 +156,8 @@
     void releaseAnimation(Animation*) const;
     bool parseAnimationDesc(Animation&);
     bool preloadZip(Animation &animation);
+    void findBootAnimationFile();
+    bool preloadAnimation();
 
     void checkExit();
 
@@ -182,6 +185,7 @@
     SortedVector<String8> mLoadedFiles;
     sp<TimeCheckThread> mTimeCheckThread = nullptr;
     sp<Callbacks> mCallbacks;
+    Animation* mAnimation = nullptr;
 };
 
 // ---------------------------------------------------------------------------