Adds a prerenderer watchdog timer.

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 d7798c4c5b26e9bbda7b181d86aec2a11033d958..a980601e700092b09674b9e44937c2e728a54159 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/logging.h"
+#include "base/time/time.h"
 #include "components/offline_pages/background/offliner_factory.h"
 #include "components/offline_pages/background/offliner_policy.h"
 #include "components/offline_pages/background/request_picker.h"
@@ -24,6 +25,12 @@ const Scheduler::TriggerConditions kUserRequestTriggerConditions(
     false /* require_power_connected */,
     50 /* minimum_battery_percentage */,
     false /* require_unmetered_network */);
+
+// Timeout is 3 minutes based on the size of Marshmallow doze mode
+// maintenance window.  TODO(petewil): Find the optimal timeout based

[dougarnett, 2016/06/30 19:16:48]

maybe line break before TODO

[dewittj, 2016/06/30 20:38:33]

Please make a bug specifically to find this number out, and reference it here.

[Pete Williamson, 2016/07/01 17:16:54]

Done.

[Pete Williamson, 2016/07/01 17:16:55]

Done.

+// on data for 2G connections and common EM websites.

[dougarnett, 2016/06/30 19:16:48]

another TODO might be to move this value into Policy object

[Pete Williamson, 2016/07/01 17:16:55]

Done.

+long OFFLINER_TIMEOUT_SECONDS = 180;

[dewittj, 2016/06/30 20:38:33]

If this is exactly the marshmallow timeout, then the timer might not actually
fire when you want it to.  Perhaps use something slightly shorter like 180 - 30?

[Pete Williamson, 2016/07/01 17:16:54]

Done.

+
 }  // namespace
 
 RequestCoordinator::RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
@@ -32,6 +39,7 @@ RequestCoordinator::RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
                                        std::unique_ptr<Scheduler> scheduler)
     : is_busy_(false),
       is_canceled_(false),
+      offliner_timeout_(OFFLINER_TIMEOUT_SECONDS),
       offliner_(nullptr),
       policy_(std::move(policy)),
       factory_(std::move(factory)),
@@ -81,6 +89,9 @@ void RequestCoordinator::StopProcessing() {
   is_canceled_ = true;
   if (offliner_ && is_busy_)
     offliner_->Cancel();
+
+  // Return control to the scheduler when there is no more to do.

[dougarnett, 2016/06/30 19:16:48]

Think this comment needs some rewording. Perhaps
// Let scheduler know we are now done with processing.

[Pete Williamson, 2016/07/01 17:16:55]

Done (changed here and in RequestQueueEmpty)

+  scheduler_callback_.Run(true);
 }
 
 // Returns true if the caller should expect a callback, false otherwise. For
@@ -143,6 +154,11 @@ void RequestCoordinator::SendRequestToOffliner(const SavePageRequest& request) {
   offliner_->LoadAndSave(request,
                          base::Bind(&RequestCoordinator::OfflinerDoneCallback,
                                     weak_ptr_factory_.GetWeakPtr()));
+
+  // Start a watchdog timer to catch pre-renders running too long
+  watchdog_timer_.Start(
+      FROM_HERE, base::TimeDelta::FromSeconds(offliner_timeout_), this,
+      &RequestCoordinator::StopProcessing);
 }
 
 void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
@@ -155,6 +171,7 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
       "Saved",
       request.request_id());
   last_offlining_status_ = status;
+  watchdog_timer_.Stop();
 
   is_busy_ = false;