Don't assume that the permission manager exists.

content/browser/push_messaging/push_messaging_manager.cc

 // Copyright 2014 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 "content/browser/push_messaging/push_messaging_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 404 matching lines @@
                        callback, data,
                        PUSH_REGISTRATION_STATUS_INCOGNITO_PERMISSION_DENIED));
       } else {
         RenderFrameHost* render_frame_host =
             RenderFrameHost::FromID(render_process_id_, data.render_frame_id);
         WebContents* web_contents =
             WebContents::FromRenderFrameHost(render_frame_host);
         if (web_contents) {
           web_contents->GetMainFrame()->AddMessageToConsole(
               CONSOLE_MESSAGE_LEVEL_ERROR, kIncognitoPushUnsupportedMessage);
+
+          BrowserContext* browser_context = web_contents->GetBrowserContext();
+
+          // It's valid for embedders to return a null permission manager.
+          // Immediately reject the permission request when this happens.
+          if (!browser_context->GetPermissionManager()) {
+            BrowserThread::PostTask(
+                BrowserThread::IO, FROM_HERE,
+                base::Bind(
+                    &PushMessagingManager::SendSubscriptionError, io_parent_,
+                    callback, data,
+                    PUSH_REGISTRATION_STATUS_INCOGNITO_PERMISSION_DENIED));
+
+            return;
+          }
+
           // Request push messaging permission (which will fail, since
           // notifications aren't supported in incognito), so the website can't
           // detect whether incognito is active.
-          web_contents->GetBrowserContext()
-              ->GetPermissionManager()
-              ->RequestPermission(
-                  PermissionType::PUSH_MESSAGING, render_frame_host,
-                  data.requesting_origin, false /* user_gesture */,
-                  base::Bind(&PushMessagingManager::Core::
-                                 DidRequestPermissionInIncognito,
-                             weak_factory_ui_to_ui_.GetWeakPtr(), callback,
-                             data));
+          browser_context->GetPermissionManager()->RequestPermission(
+              PermissionType::PUSH_MESSAGING, render_frame_host,
+              data.requesting_origin, false /* user_gesture */,
+              base::Bind(
+                  &PushMessagingManager::Core::DidRequestPermissionInIncognito,
+                  weak_factory_ui_to_ui_.GetWeakPtr(), callback, data));
         }
       }
     }
     return;
   }
 
   if (data.FromDocument()) {
     push_service->SubscribeFromDocument(
         data.requesting_origin, data.service_worker_registration_id,
         render_process_id_, data.render_frame_id, data.options,
@@ skipping 456 matching lines @@
 PushMessagingService* PushMessagingManager::Core::service() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   RenderProcessHost* process_host =
       RenderProcessHost::FromID(render_process_id_);
   return process_host
              ? process_host->GetBrowserContext()->GetPushMessagingService()
              : nullptr;
 }
 
 }  // namespace content