webapps: Add cleanup task when opening up WebappActivity to clean old web apps

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
index f34f440c6453cc952ab2ea360bb3b90afd4ecc2c..5803d30cc7c320707a3d5ae69b8ed335c1959eee 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
@@ -52,6 +52,7 @@ public class WebappActivity extends FullScreenActivity {
 
     private final WebappInfo mWebappInfo;
     private AsyncTask<WebappActivity, Void, Void> mCleanupTask;
+    private boolean mOldWebappCleanupStarted;
 
     private WebContentsObserver mWebContentsObserver;
 
@@ -156,6 +157,13 @@ public class WebappActivity extends FullScreenActivity {
             updateTaskDescription();
         }
         super.onResume();
+
+        // Kick off the old web app cleanup (if we haven't alread) now that we have queued the
+        // current web app's storage to be opened.
+        if (!mOldWebappCleanupStarted) {
+            WebappRegistry.unregisterOldWebapps(this, System.currentTimeMillis());
+            mOldWebappCleanupStarted = true;
+        }
     }
 
     @Override