Expose a method in VariationsService to trigger a seed fetch.

chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc

Index: chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc
diff --git a/chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc b/chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc
index 77148617bfcb9747711027767e5da2ae427bdca2..b97cc11a81320151ae0402f047c21f8fc777a6ff 100644
--- a/chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc
+++ b/chrome/browser/metrics/variations/variations_request_scheduler_mobile.cc
@@ -11,6 +11,9 @@ namespace chrome_variations {
 
 namespace {
 
+// Time before attempting a seed fetch after a ScheduleFetch(), in seconds.
+const int kScheduleFetchDelaySeconds = 5;
+
 // Time between seed fetches, in hours.
 const int kSeedFetchPeriodHours = 5;
 
@@ -41,6 +44,17 @@ void VariationsRequestSchedulerMobile::Start() {
 void VariationsRequestSchedulerMobile::Reset() {
 }
 
+void VariationsRequestSchedulerMobile::ScheduleFetch() {

[Alexei Svitkine (slow), 2014/02/12 21:17:44]

What's the reason for this being separate from
ScheduleFetchShortly()/ForceFetch()?

[rkaplow, 2014/02/12 22:51:52]

ScheduleFetchShortly()/ForceFetch() is doing something slightly different. The
intention is to recover from network errors or other problems, and it is
currently waiting 5 minutes. It's also not checking that we already have a fresh
seed. 

it was a bit tricky to merge them as I want the seed check to be after the 5
second delay - because on a fresh application start it also counts as an
Foreground event, which would trigger two separate calls if the check happened
immediately.

+  // Since Start() launches a one-off execution, we can reuse it here. Also
+  // note that since Start() verifies that the seed needs to be refreshed, we
+  // do not verify here.
+  schedule_fetch_timer_.Start(
+      FROM_HERE,
+      base::TimeDelta::FromSeconds(kScheduleFetchDelaySeconds),
+      this,
+      &VariationsRequestSchedulerMobile::Start);
+}
+
 // static
 VariationsRequestScheduler* VariationsRequestScheduler::Create(
     const base::Closure& task,