Adds a prerenderer watchdog timer.

components/offline_pages/background/request_coordinator.h

Index: components/offline_pages/background/request_coordinator.h
diff --git a/components/offline_pages/background/request_coordinator.h b/components/offline_pages/background/request_coordinator.h
index 624808c3962a529b4d05aed882a32eca670abbd2..18c25bd40f484f081f72d54490f39f13890e06a4 100644
--- a/components/offline_pages/background/request_coordinator.h
+++ b/components/offline_pages/background/request_coordinator.h
@@ -10,6 +10,7 @@
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/offline_pages/background/device_conditions.h"
 #include "components/offline_pages/background/offliner.h"
@@ -117,6 +118,10 @@ class RequestCoordinator : public KeyedService {
   // if needed.
   void GetOffliner();
 
+  void SetOfflinerTimeoutForTest(long timeout) {
+    offliner_timeout_ = timeout;
+  }
+
   friend class RequestCoordinatorTest;
 
   // The offliner can only handle one request at a time - if the offliner is
@@ -125,6 +130,8 @@ class RequestCoordinator : public KeyedService {
   bool is_busy_;
   // True if the current request has been canceled.
   bool is_canceled_;
+  // How long to wait for an offliner before giving up.

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

... an offliner request ... ?

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

Done.

+  long offliner_timeout_;

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

Please use base::TimeDelta here so the units are unambiguous.

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

Done.

   // Unowned pointer to the current offliner, if any.
   Offliner* offliner_;
   // RequestCoordinator takes over ownership of the policy
@@ -143,6 +150,8 @@ class RequestCoordinator : public KeyedService {
   base::Callback<void(bool)> scheduler_callback_;
   // Logger to record events.
   RequestCoordinatorEventLogger event_logger_;
+  // Timer to watch for pre-render attempts running too long.
+  base::OneShotTimer watchdog_timer_;
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;