Fix occasional crash in TryNextRequest

components/offline_pages/background/request_coordinator.cc

Index: components/offline_pages/background/request_coordinator.cc
diff --git a/components/offline_pages/background/request_coordinator.cc b/components/offline_pages/background/request_coordinator.cc
index d1d380b005043d4a541073c48f6832a005653476..829fc85a3a68d28ba235b499e80cebe15fd99b48 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -136,6 +136,7 @@ RequestCoordinator::RequestCoordinator(
       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);
@@ -239,6 +240,7 @@ bool RequestCoordinator::CancelActiveRequestIfItMatches(
     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;
     }
   }
@@ -485,6 +487,7 @@ void RequestCoordinator::TryNextRequest() {
     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;