Fix WebAPK crashes on launch on Jellybean.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.webapps;
 
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
@@ skipping 134 matching lines @@
         super.onSaveInstanceState(outState);
         if (getActivityTab() != null) {
             outState.putInt(BUNDLE_TAB_ID, getActivityTab().getId());
             outState.putString(BUNDLE_TAB_URL, getActivityTab().getUrl());
         }
     }
 
     @Override
     public void onStartWithNative() {
         super.onStartWithNative();
-        mDirectoryManager.cleanUpDirectories(this, getId());
+        mDirectoryManager.cleanUpDirectories(this, getActivityId());
     }
 
     @Override
     public void onStopWithNative() {
         super.onStopWithNative();
         mDirectoryManager.cancelCleanup();
         if (getActivityTab() != null) saveState(getActivityDirectory());
         if (getFullscreenManager() != null) {
             getFullscreenManager().setPersistentFullscreenMode(false);
         }
@@ skipping 327 matching lines @@
         ApiCompatibilityUtils.setTaskDescription(this, title, icon,
                 ColorUtils.getOpaqueColor(taskDescriptionColor));
         ApiCompatibilityUtils.setStatusBarColor(getWindow(), statusBarColor);
     }
 
     @Override
     protected void setStatusBarColor(Tab tab, int color) {
         // Intentionally do nothing as WebappActivity explicitly sets status bar color.
     }
 
-    /** Returns a unique identifier for this WebappActivity. */
-    protected String getId() {
+    /**
+     * Returns a unique identifier for this WebappActivity.
+     * Note: do not call this function when you need {@link WebappInfo#id()}. Subclasses like
+     * WebappManagedActivity and WebApkManagedActivity overwrite this function and return the
+     * index of the activity.
+     */
+    protected String getActivityId() {
         return mWebappInfo.id();
     }
 
     /**
      * Get the active directory by this web app.
      *
      * @return The directory used for the current web app.
      */
     @Override
     protected final File getActivityDirectory() {
-        return mDirectoryManager.getWebappDirectory(this, getId());
+        return mDirectoryManager.getWebappDirectory(this, getActivityId());
     }
 
     private void hideSplashScreen(final int reason) {
         if (mSplashScreen == null) return;
 
         mSplashScreen.animate()
                 .alpha(0f)
                 .withEndAction(new Runnable() {
                     @Override
                     public void run() {
@@ skipping 49 matching lines @@
         return new WebappDelegateFactory(this);
     }
 
     // We're temporarily disable CS on webapp since there are some issues. (http://crbug.com/471950)
     // TODO(changwan): re-enable it once the issues are resolved.
     @Override
     protected boolean isContextualSearchAllowed() {
         return false;
     }
 }