[Download Home] Deal with the infinite spinny

Because of timing delays, and because cancelling a Runnable doesn't
guarantee that it won't run, the LoadingView can get into a state
where it posts a task to animate itself showing up on screen but it
doesn't re-check if it still needs to be visible.

BUG=641262

Review-Url: https://codereview.chromium.org/2319213004
Cr-Commit-Position: refs/heads/master@{#417417}

chrome/android/java/src/org/chromium/chrome/browser/widget/LoadingView.java

@@ -26,12 +26,20 @@ public class LoadingView extends ProgressBar {
     private final Runnable mDelayedShow = new Runnable() {
         @Override
         public void run() {
+            if (!mShouldShow) return;
             mStartTime = SystemClock.elapsedRealtime();
             setVisibility(View.VISIBLE);
             setAlpha(1.0f);
         }
     };
 
+    /**
+     * Tracks whether the View should be displayed when {@link #mDelayedShow} is run.  Android
+     * doesn't always cancel a Runnable when requested, meaning that the View could be hidden before
+     * it even has a chance to be shown.
+     */
+    private boolean mShouldShow;
+
     // Material loading design spec requires us to show progress spinner at least 500ms, so we need
     // this delayed runnable to implement that.
     private final Runnable mDelayedHide = new Runnable() {
@@ -67,6 +75,7 @@ public class LoadingView extends ProgressBar {
     public void showLoadingUI() {
         removeCallbacks(mDelayedShow);
         removeCallbacks(mDelayedHide);
+        mShouldShow = true;
 
         setVisibility(GONE);
         postDelayed(mDelayedShow, LOADING_ANIMATION_DELAY_MS);
@@ -79,6 +88,7 @@ public class LoadingView extends ProgressBar {
     public void hideLoadingUI() {
         removeCallbacks(mDelayedShow);
         removeCallbacks(mDelayedHide);
+        mShouldShow = false;
 
         if (getVisibility() == VISIBLE) {
             postDelayed(mDelayedHide, Math.max(0,