Fix occasional crash in TryNextRequest

components/offline_pages/background/request_coordinator.cc

 // 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.
 
 #include "components/offline_pages/background/request_coordinator.h"
 
 #include <limits>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 118 matching lines @@
       test_connection_type_(),
       offliner_(nullptr),
       policy_(std::move(policy)),
       factory_(std::move(factory)),
       queue_(std::move(queue)),
       scheduler_(std::move(scheduler)),
       policy_controller_(new ClientPolicyController()),
       network_quality_estimator_(network_quality_estimator),
       active_request_(nullptr),
       last_offlining_status_(Offliner::RequestStatus::UNKNOWN),
+      scheduler_callback_(base::Bind(&EmptySchedulerCallback)),
       immediate_schedule_callback_(base::Bind(&EmptySchedulerCallback)),
       weak_ptr_factory_(this) {
   DCHECK(policy_ != nullptr);
   picker_.reset(
       new RequestPicker(queue_.get(), policy_.get(), this, &event_logger_));
 }
 
 RequestCoordinator::~RequestCoordinator() {}
 
 int64_t RequestCoordinator::SavePageLater(const GURL& url,
@@ skipping 83 matching lines @@
 
 bool RequestCoordinator::CancelActiveRequestIfItMatches(
     const std::vector<int64_t>& request_ids) {
   // If we have a request in progress and need to cancel it, call the
   // pre-renderer to cancel.  TODO Make sure we remove any page created by the
   // prerenderer if it doesn't get the cancel in time.
   if (active_request_ != nullptr) {
     if (request_ids.end() != std::find(request_ids.begin(), request_ids.end(),
                                        active_request_->request_id())) {
       StopPrerendering(Offliner::RequestStatus::REQUEST_COORDINATOR_CANCELED);
+      active_request_.reset(nullptr);
       return true;
     }
   }
 
   return false;
 }
 
 void RequestCoordinator::AbortRequestAttempt(SavePageRequest* request) {
   request->MarkAttemptAborted();
   if (request->started_attempt_count() >= policy_->GetMaxStartedTries()) {
@@ skipping 226 matching lines @@
   // If there is no time left in the budget, return to the scheduler.
   // We do not remove the pending task that was set up earlier in case
   // we run out of time, so the background scheduler will return to us
   // at the next opportunity to run background tasks.
   if (base::Time::Now() - operation_start_time_ >
       base::TimeDelta::FromSeconds(
           policy_->GetBackgroundProcessingTimeBudgetSeconds())) {
     is_starting_ = false;
 
     // Let the scheduler know we are done processing.
+    // TODO: Make sure the scheduler callback is valid before running it.

[dougarnett, 2016/10/21 16:46:02]

wonder if we could base on processing_state != STOPPED ?

     scheduler_callback_.Run(true);
 
     return;
   }
 
   // Choose a request to process that meets the available conditions.
   // This is an async call, and returns right away.
   picker_->ChooseNextRequest(base::Bind(&RequestCoordinator::RequestPicked,
                                         weak_ptr_factory_.GetWeakPtr()),
                              base::Bind(&RequestCoordinator::RequestNotPicked,
@@ skipping 252 matching lines @@
 
 ClientPolicyController* RequestCoordinator::GetPolicyController() {
   return policy_controller_.get();
 }
 
 void RequestCoordinator::Shutdown() {
   network_quality_estimator_ = nullptr;
 }
 
 }  // namespace offline_pages