Add expiration policy, code to check it, and a test.

components/offline_pages/background/request_picker.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_picker.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "components/offline_pages/background/save_page_request.h"
 
@@ skipping 96 matching lines @@
     }
   }
 
   // If we have already tried this page the max number of times, it is not
   // eligible to try again.
   // TODO(petewil): Instead, we should have code to remove the page from the
   // queue after the last retry.
   if (request.attempt_count() >= policy_->GetMaxRetries())
     return false;
 
+  // If the request is expired, do not consider it.
+  base::TimeDelta requestAge = base::Time::Now() - request.creation_time();
+  if (requestAge >
+      base::TimeDelta::FromSeconds(policy_->GetPageExpirationTimeInSeconds()))
+    return false;

[dougarnett, 2016/07/27 15:40:41]

Maybe add TODO wrt need to remove this from the queue somehow

[Pete Williamson, 2016/07/27 17:20:06]

Done.

+
   // If this request is not active yet, return false.
   // TODO(petewil): If the only reason we return nothing to do is that we have
   // inactive requests, we still want to try again later after their activation
   // time elapses, we shouldn't take ourselves completely off the scheduler.
   if (request.activation_time() > base::Time::Now())
     return false;
 
   return true;
 }
 
@@ skipping 70 matching lines @@
   int result = signum(difference.InMilliseconds());
 
   // Flip the direction of comparison if policy prefers fewer retries.
   if (earlier_requests_better_)
     result *= -1;
 
   return result;
 }
 
 }  // namespace offline_pages