Hide modal permission prompts on Android upon tab navigation/destruction

chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java

 // Copyright 2016 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.permissions;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.DialogInterface;
 import android.support.annotation.IntDef;
@@ skipping 71 matching lines @@
 
     /**
      * Queues a modal permission dialog for display. If there are currently no dialogs on screen, it
      * will be displayed immediately. Otherwise, it will be displayed as soon as the user responds
      * to the current dialog.
      * @param context  The context to use to get the dialog layout.
      * @param delegate The wrapper for the native-side permission delegate.
      */
     private void queueDialog(PermissionDialogDelegate delegate) {
         mRequestQueue.add(delegate);
+        delegate.setDialogController(this);
         scheduleDisplay();
     }
 
     private void scheduleDisplay() {
         if (mDialog == null && !mRequestQueue.isEmpty()) showDialog();
     }
 
     @VisibleForTesting
     public AlertDialog getCurrentDialogForTesting() {
         return mDialog;
     }
 
+    @VisibleForTesting
+    public int getQueueLengthForTesting() {
+        return mRequestQueue.size();
+    }
+
     @Override
     public void onAndroidPermissionAccepted() {
         mDialogDelegate.onAccept(mSwitchView.isChecked());
         destroyDelegate();
         scheduleDisplay();
     }
 
     @Override
     public void onAndroidPermissionCanceled() {
         mDialogDelegate.onDismiss();
@@ skipping 72 matching lines @@
                     public void onClick(DialogInterface dialog, int id) {
                         mDecision = CANCELED;
                     }
                 });
 
         // Called when the dialog is dismissed. Interacting with either button in the dialog will
         // call this handler after the primary/secondary handler.
         mDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
             @Override
             public void onDismiss(DialogInterface dialog) {
-                // For some reason this is ocassionally null. See crbug.com/708562.
+                // Null if dismiss initiated by C++, or for some unknown reason (crbug.com/708562).
                 if (mDialogDelegate == null) {
                     scheduleDisplay();
+                    return;
                 }
 
                 mDialog = null;
                 if (mDecision == ACCEPTED) {
                     // Request Android permissions if necessary. This will call back into either
                     // onAndroidPermissionAccepted or onAndroidPermissionCanceled, which will
                     // schedule the next permission dialog. If it returns false, no system level
                     // permissions need to be requested, so just run the accept callback.
                     if (!AndroidPermissionRequester.requestAndroidPermissions(
                                 mDialogDelegate.getTab(), mDialogDelegate.getContentSettingsTypes(),
@@ skipping 37 matching lines @@
                     mDecision = NOT_DECIDED;
                     delegate.onLinkClicked();
                     if (mDialog != null) mDialog.dismiss();
                 }
             }, spanStart, fullString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
         }
 
         return fullString;
     }
 
+    public void dismissFromNative(PermissionDialogDelegate delegate) {
+        if (mDialogDelegate == delegate) {
+            mDialogDelegate = null;
+            AlertDialog dialog = mDialog;
+            mDialog = null;
+            dialog.dismiss();
+        } else {
+            assert mRequestQueue.contains(delegate);
+            mRequestQueue.remove(delegate);
+        }
+        delegate.destroy();
+    }
+
     private void destroyDelegate() {
         mDialogDelegate.destroy();
         mDialogDelegate = null;
     }
 }