[Sync] Add client-side plumbing for server control of sessions commit delay

chrome/browser/sync/engine/sync_scheduler_unittest.cc

Index: chrome/browser/sync/engine/sync_scheduler_unittest.cc
diff --git a/chrome/browser/sync/engine/sync_scheduler_unittest.cc b/chrome/browser/sync/engine/sync_scheduler_unittest.cc
index 18107065f830a2500d0cff6b3046342fcf08e3af..4f1058d78498938535b0fd62a2846e6520035ee7 100644
--- a/chrome/browser/sync/engine/sync_scheduler_unittest.cc
+++ b/chrome/browser/sync/engine/sync_scheduler_unittest.cc
@@ -629,6 +629,37 @@ TEST_F(SyncSchedulerTest, PollIntervalUpdate) {
   AnalyzePollRun(records, kMinNumSamples, optimal_start, poll2);
 }
 
+// Test that the sessions commit delay is updated when needed.
+TEST_F(SyncSchedulerTest, SessionsCommitDelay) {
+  SyncShareRecords records;
+  TimeDelta delay1(TimeDelta::FromMilliseconds(120));
+  TimeDelta delay2(TimeDelta::FromMilliseconds(30));
+  scheduler()->OnReceivedSessionsCommitDelay(delay1);
+
+  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
+      .WillOnce(
+          DoAll(
+              WithArg<0>(
+                  sessions::test_util::SimulateSessionsCommitDelayUpdate(
+                      delay2)),
+              Invoke(sessions::test_util::SimulateSuccess),
+              QuitLoopNowAction()));
+
+  EXPECT_EQ(delay1, scheduler()->sessions_commit_delay());
+  StartSyncScheduler(SyncScheduler::NORMAL_MODE);
+  RunLoop();
+
+  EXPECT_EQ(delay1, scheduler()->sessions_commit_delay());
+  syncable::ModelTypeBitSet model_types;
+  model_types[syncable::BOOKMARKS] = true;
+  scheduler()->ScheduleNudge(
+      zero(), NUDGE_SOURCE_LOCAL, model_types, FROM_HERE);
+  RunLoop();
+
+  EXPECT_EQ(delay2, scheduler()->sessions_commit_delay());
+  scheduler()->Stop();
+}
+
 // Test that a sync session is run through to completion.
 TEST_F(SyncSchedulerTest, HasMoreToSync) {
   EXPECT_CALL(*syncer(), SyncShare(_,_,_))