Fix crash due to VisibilityTimerTabHelper not being cancelled

chrome/browser/notifications/notification_permission_context.cc

 // 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.
 
 #include "chrome/browser/notifications/notification_permission_context.h"
 
-#include <queue>
+#include <algorithm>
+#include <deque>
 
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/rand_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/notifications/desktop_notification_profile_util.h"
 #include "chrome/browser/permissions/permission_request_id.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 13 matching lines @@
 class VisibilityTimerTabHelper
     : public content::WebContentsObserver,
       public content::WebContentsUserData<VisibilityTimerTabHelper> {
  public:
   ~VisibilityTimerTabHelper() override {}
 
   // Runs |task| after the WebContents has been visible for a consecutive
   // duration of at least |visible_delay|.
   void PostTaskAfterVisibleDelay(const tracked_objects::Location& from_here,
                                  const base::Closure& task,
-                                 base::TimeDelta visible_delay);
+                                 base::TimeDelta visible_delay,
+                                 const PermissionRequestID& id);
+
+  // Deletes any earlier task(s) that match |id|.
+  void CancelTask(const PermissionRequestID& id);
 
   // WebContentsObserver:
   void WasShown() override;
   void WasHidden() override;
   void WebContentsDestroyed() override;
 
  private:
   friend class content::WebContentsUserData<VisibilityTimerTabHelper>;
   explicit VisibilityTimerTabHelper(content::WebContents* contents);
 
   void RunTask(const base::Closure& task);
 
   bool is_visible_;
-  std::queue<scoped_ptr<base::Timer>> task_queue_;
+
+  struct Task {
+    Task(const PermissionRequestID& id, scoped_ptr<base::Timer> timer)
+        : id(id), timer(std::move(timer)) {}
+    PermissionRequestID id;
+    scoped_ptr<base::Timer> timer;
+  };
+  std::deque<Task> task_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(VisibilityTimerTabHelper);
 };
 
 VisibilityTimerTabHelper::VisibilityTimerTabHelper(
     content::WebContents* contents)
     : content::WebContentsObserver(contents) {
   if (!contents->GetMainFrame()) {
     is_visible_ = false;
   } else {
     switch (contents->GetMainFrame()->GetVisibilityState()) {
       case blink::WebPageVisibilityStateHidden:
       case blink::WebPageVisibilityStatePrerender:
         is_visible_ = false;
         break;
       case blink::WebPageVisibilityStateVisible:
         is_visible_ = true;
         break;
     }
   }
 }
 
 void VisibilityTimerTabHelper::PostTaskAfterVisibleDelay(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
-    base::TimeDelta visible_delay) {
+    base::TimeDelta visible_delay,
+    const PermissionRequestID& id) {
+  if (web_contents()->IsBeingDestroyed())
+    return;
   // Safe to use Unretained, as destroying this will destroy task_queue_, hence
   // cancelling all timers.
-  task_queue_.push(make_scoped_ptr(new base::Timer(
+  scoped_ptr<base::Timer> timer(new base::Timer(
       from_here, visible_delay, base::Bind(&VisibilityTimerTabHelper::RunTask,
                                            base::Unretained(this), task),
-      false /* is_repeating */)));
-  DCHECK(!task_queue_.back()->IsRunning());
+      false /* is_repeating */));
+  task_queue_.push_back(Task(id, std::move(timer)));
+  DCHECK(!task_queue_.back().timer->IsRunning());
   if (is_visible_ && task_queue_.size() == 1)
-    task_queue_.front()->Reset();
+    task_queue_.front().timer->Reset();
+}
+
+void VisibilityTimerTabHelper::CancelTask(const PermissionRequestID& id) {
+  bool deleting_front = task_queue_.front().id == id;
+  task_queue_.erase(
+      std::remove_if(task_queue_.begin(), task_queue_.end(),
+                     [id](const Task& task) { return task.id == id; }),
+      task_queue_.end());
+  if (!task_queue_.empty() && is_visible_ && deleting_front)
+    task_queue_.front().timer->Reset();
 }

[Peter Beverloo, 2016/02/16 22:43:28]

Personally I would add a bunch of blank lines to further help readability like
you do in the unit test (probably after lines 96, 102, 104, 110, 114), but I'll
leave that up to you.

[johnme, 2016/02/17 13:32:07]

Done.

 
 void VisibilityTimerTabHelper::WasShown() {
   if (!is_visible_ && !task_queue_.empty())
-    task_queue_.front()->Reset();
+    task_queue_.front().timer->Reset();
   is_visible_ = true;
 }
 
 void VisibilityTimerTabHelper::WasHidden() {
   if (is_visible_ && !task_queue_.empty())
-    task_queue_.front()->Stop();
+    task_queue_.front().timer->Stop();
   is_visible_ = false;
 }
 
 void VisibilityTimerTabHelper::WebContentsDestroyed() {
-  // Delete ourselves, to avoid running tasks after WebContents is destroyed.
-  web_contents()->RemoveUserData(UserDataKey());
-  // |this| has been deleted now.
+  task_queue_.clear();
 }
 
 void VisibilityTimerTabHelper::RunTask(const base::Closure& task) {
   DCHECK(is_visible_);
   task.Run();
-  task_queue_.pop();
-  if (!task_queue_.empty()) {
-    task_queue_.front()->Reset();
-    return;
-  }
-  web_contents()->RemoveUserData(UserDataKey());
-  // |this| has been deleted now.
+  task_queue_.pop_front();
+  if (!task_queue_.empty())
+    task_queue_.front().timer->Reset();
 }
 
 }  // namespace
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(VisibilityTimerTabHelper);
 
 NotificationPermissionContext::NotificationPermissionContext(Profile* profile)
     : PermissionContextBase(profile,
                             content::PermissionType::NOTIFICATIONS,
                             CONTENT_SETTINGS_TYPE_NOTIFICATIONS),
       weak_factory_ui_thread_(this) {}
 
 NotificationPermissionContext::~NotificationPermissionContext() {}
 
 void NotificationPermissionContext::ResetPermission(
     const GURL& requesting_origin,
     const GURL& embedder_origin) {
   DesktopNotificationProfileUtil::ClearSetting(
       profile(), ContentSettingsPattern::FromURLNoWildcard(requesting_origin));
 }
 
+void NotificationPermissionContext::CancelPermissionRequest(
+    content::WebContents* web_contents,
+    const PermissionRequestID& id) {
+  if (profile()->IsOffTheRecord()) {
+    VisibilityTimerTabHelper::FromWebContents(web_contents)->CancelTask(id);
+  } else {
+    PermissionContextBase::CancelPermissionRequest(web_contents, id);
+  }
+}
+
 void NotificationPermissionContext::DecidePermission(
     content::WebContents* web_contents,
     const PermissionRequestID& id,
     const GURL& requesting_origin,
     const GURL& embedding_origin,
     bool user_gesture,
     const BrowserPermissionCallback& callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   // Notifications permission is always denied in incognito. To prevent sites
   // from using that to detect whether incognito mode is active, we deny after a
   // random time delay, to simulate a user clicking a bubble/infobar. See also
   // ContentSettingsRegistry::Init, which marks notifications as
   // INHERIT_IN_INCOGNITO_EXCEPT_ALLOW, and
   // PermissionMenuModel::PermissionMenuModel which prevents users from manually
   // allowing the permission.
   if (profile()->IsOffTheRecord()) {
     // Random number of seconds in the range [1.0, 2.0).
     double delay_seconds = 1.0 + 1.0 * base::RandDouble();
     VisibilityTimerTabHelper::CreateForWebContents(web_contents);
     VisibilityTimerTabHelper::FromWebContents(web_contents)
         ->PostTaskAfterVisibleDelay(
             FROM_HERE,
             base::Bind(&NotificationPermissionContext::NotifyPermissionSet,
                        weak_factory_ui_thread_.GetWeakPtr(), id,
                        requesting_origin, embedding_origin, callback,
                        true /* persist */, CONTENT_SETTING_BLOCK),
-            base::TimeDelta::FromSecondsD(delay_seconds));
+            base::TimeDelta::FromSecondsD(delay_seconds), id);
     return;
   }
 
   PermissionContextBase::DecidePermission(web_contents, id, requesting_origin,
                                           embedding_origin, user_gesture,
                                           callback);
 }
 
 // Unlike other permission types, granting a notification for a given origin
 // will not take into account the |embedder_origin|, it will only be based
@@ skipping 12 matching lines @@
                                                     requesting_origin);
   } else {
     DesktopNotificationProfileUtil::DenyPermission(profile(),
                                                    requesting_origin);
   }
 }
 
 bool NotificationPermissionContext::IsRestrictedToSecureOrigins() const {
   return false;
 }