Fix DCHECK failure in extension_updater when scheduling first check

chrome/browser/extensions/updater/extension_updater.cc

 // Copyright (c) 2012 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 "chrome/browser/extensions/updater/extension_updater.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 160 matching lines @@
   // If someone's testing with a quick frequency, just allow it.
   if (frequency_seconds_ < kStartupWaitSeconds)
     return TimeDelta::FromSeconds(frequency_seconds_);
 
   // If we've never scheduled a check before, start at a random time up to
   // frequency_seconds_ away.
   if (!prefs_->HasPrefPath(pref_names::kNextUpdateCheck))
     return TimeDelta::FromSeconds(
         RandInt(kStartupWaitSeconds, frequency_seconds_));
 
+  // Read the persisted next check time, and use that if it isn't in the past
+  // or too far in the future (this can happen with system clock changes).
   Time saved_next = Time::FromInternalValue(prefs_->GetInt64(
       pref_names::kNextUpdateCheck));
-
   Time now = Time::Now();
-
-  // Read the persisted next check time, and use that if it isn't in the past
-  // or too far in the future (this can happen with system clock changes).
-  if (saved_next > now &&
-      saved_next < now + TimeDelta::FromSeconds(frequency_seconds_)) {
+  base::Time earliest = now + TimeDelta::FromSeconds(1);

[lazyboy, 2016/12/10 00:10:15]

The value 1 is coming from  ExtensionUpdater::ScheduleNextCheck, right? I'd put
this in a constant in this file's anonymous namspace.

Also add a dcheck in the constructor to ensure frequence_seconds_ is greater
than this. It already checks for >= 5, but that value can change independently.

[asargent_no_longer_on_chrome, 2016/12/14 23:01:19]

Done.

+  base::Time latest = now + TimeDelta::FromSeconds(frequency_seconds_);
+  if (saved_next > earliest && saved_next < latest) {
     return saved_next - now;
   }
 
   // In most cases we'll get here because the persisted next check time passed
   // while we weren't running, so pick something soon.
   return TimeDelta::FromSeconds(
       RandInt(kStartupWaitSeconds, kStartupWaitSeconds * 5));
 }
 
 void ExtensionUpdater::Start() {
@@ skipping 398 matching lines @@
   const InProgressCheck& request = requests_in_progress_[request_id];
   if (request.in_progress_ids_.empty()) {
     VLOG(2) << "Finished update check " << request_id;
     if (!request.callback.is_null())
       request.callback.Run();
     requests_in_progress_.erase(request_id);
   }
 }
 
 }  // namespace extensions