Speculative fix for the NPE in dispatchGetDisplayList

chrome/android/java/src/org/chromium/chrome/browser/SwipeRefreshHandler.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;
 
 import android.content.Context;
 import android.view.ViewGroup.LayoutParams;
 
 import org.chromium.base.TraceEvent;
@@ skipping 24 matching lines @@
 
     // The ContentViewCore with which the handler is associated. The handler
     // will set/unset itself as the default OverscrollRefreshHandler as the
     // association changes.
     private ContentViewCore mContentViewCore;
 
     // Async runnable for ending the refresh animation after the page first
     // loads a frame. This is used to provide a reasonable minimum animation time.
     private Runnable mStopRefreshingRunnable;
 
+    // Handles removing the layout from the view hierarchy.  This is posted to ensure it does not
+    // conflict with pending Android draws.
+    private Runnable mDetachLayoutRunnable;
+
     // Accessibility utterance used to indicate refresh activation.
     private String mAccessibilityRefreshString;
 
     /**
      * Simple constructor to use when creating an OverscrollRefresh instance from code.
      *
      * @param context The associated context.
      */
     public SwipeRefreshHandler(Context context) {
         mSwipeRefreshLayout = new SwipeRefreshLayout(context);
@@ skipping 38 matching lines @@
                 }
                 mSwipeRefreshLayout.announceForAccessibility(mAccessibilityRefreshString);
                 contentViewCore.getWebContents().getNavigationController().reloadToRefreshContent(
                         true);
                 RecordUserAction.record("MobilePullGestureReload");
             }
         });
         mSwipeRefreshLayout.setOnResetListener(new SwipeRefreshLayout.OnResetListener() {
             @Override
             public void onReset() {
-                detachSwipeRefreshLayoutIfNecessary();
+                if (mDetachLayoutRunnable != null) return;
+                mDetachLayoutRunnable = new Runnable() {
+                    @Override
+                    public void run() {
+                        mDetachLayoutRunnable = null;
+                        detachSwipeRefreshLayoutIfNecessary();
+                    }
+                };
+                mSwipeRefreshLayout.post(mDetachLayoutRunnable);
             }
         });
 
         contentViewCore.setOverscrollRefreshHandler(this);
     }
 
     /**
      * Notify the SwipeRefreshLayout that a refresh action has completed.
      * Defer the notification by a reasonable minimum to ensure sufficient
      * visiblity of the animation.
@@ skipping 36 matching lines @@
         mSwipeRefreshLayout.setEnabled(enabled);
         if (!enabled) reset();
     }
 
     private void cancelStopRefreshingRunnable() {
         if (mStopRefreshingRunnable != null) {
             mSwipeRefreshLayout.removeCallbacks(mStopRefreshingRunnable);
         }
     }
 
+    private void cancelDetachLayoutRunnable() {
+        if (mDetachLayoutRunnable != null) {
+            mSwipeRefreshLayout.removeCallbacks(mDetachLayoutRunnable);
+            mDetachLayoutRunnable = null;
+        }
+    }
+
     private Runnable getStopRefreshingRunnable() {
         if (mStopRefreshingRunnable == null) {
             mStopRefreshingRunnable = new Runnable() {
                 @Override
                 public void run() {
                     mSwipeRefreshLayout.setRefreshing(false);
                 }
             };
         }
         return mStopRefreshingRunnable;
     }
 
     // The animation view is attached/detached on-demand to minimize overlap
     // with composited SurfaceView content.
     private void attachSwipeRefreshLayoutIfNecessary() {
+        cancelDetachLayoutRunnable();
         if (mContentViewCore == null) return;
         if (mSwipeRefreshLayout.getParent() == null) {
             mContentViewCore.getContainerView().addView(mSwipeRefreshLayout);
         }
     }
 
     private void detachSwipeRefreshLayoutIfNecessary() {
+        cancelDetachLayoutRunnable();
         if (mContentViewCore == null) return;
         if (mSwipeRefreshLayout.getParent() != null) {
             mContentViewCore.getContainerView().removeView(mSwipeRefreshLayout);
         }
     }
 }