Fix bug introduced when moving animation step out from between assignments to wasAnimating and nowAnimating.

Now wasAnimating once again contains the animation state prior to the animation step.

Change-Id: I2b53bd3f62228183233ab36f0ebe44c0344d2351

Author: Craig Mautner

services/java/com/android/server/wm/WindowManagerService.java

@@ -7685,7 +7685,7 @@ private int updateWindowsAndWallpaperLocked(final long currentTime, final int dw
                     }
                 }
 
-                final boolean wasAnimating = w.mAnimating;
+                final boolean wasAnimating = w.mWasAnimating;
 
                 // If the window has moved due to its containing
                 // content frame changing, then we'd like to animate

services/java/com/android/server/wm/WindowState.java

@@ -91,6 +91,7 @@ final class WindowState implements WindowManagerPolicy.WindowState {
     boolean mAttachedHidden;    // is our parent window hidden?
     boolean mLastHidden;        // was this window last hidden?
     boolean mWallpaperVisible;  // for wallpaper, what was last vis report?
+    boolean mWasAnimating;      // Were we animating going into the most recent animation step?
 
     /**
      * The window size that was requested by the application.  These are in
@@ -979,6 +980,9 @@ boolean performShowLocked() {
     // This must be called while inside a transaction.  Returns true if
     // there is more animation to run.
     boolean stepAnimationLocked(long currentTime) {
+        // Save the animation state as it was before this step so WindowManagerService can tell if
+        // we just started or just stopped animating by comparing mWasAnimating with isAnimating().
+        mWasAnimating = isAnimating();
         if (!mService.mDisplayFrozen && mService.mPolicy.isScreenOnFully()) {
             // We will run animations as long as the display isn't frozen.