[Sync] Refactor sync configuration logic.

We remove all the pending download/configure state in SBH, in addition
to the split transaction nature of configurations themselves. This allows
us to have a single SyncScheduler::ScheduleConfiguration command that is
both synchronous (assuming it doesn't fail) and can handle
 CleanupDisabledTypes and GetKey commands.

This also now keys which datatypes need downloading by checking the
initial sync ended bits directly. This allows us to recover from a new
sync db gracefully.

BUG=129665,133061,129825
TEST=unit/integration tests

Review URL: https://chromiumcodereview.appspot.com/10483015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@142517 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 504 insertions, 228 deletions

diff --git a/sync/engine/sync_scheduler.cc b/sync/engine/sync_scheduler.cc
index f798d67..e745d19 100644
--- a/sync/engine/sync_scheduler.cc
+++ b/sync/engine/sync_scheduler.cc
@@ -68,6 +68,24 @@ bool IsActionableError(
 }
 }  // namespace
 
+ConfigurationParams::ConfigurationParams()
+    : source(GetUpdatesCallerInfo::UNKNOWN),
+      keystore_key_status(KEYSTORE_KEY_UNNECESSARY) {}
+ConfigurationParams::ConfigurationParams(
+    const sync_pb::GetUpdatesCallerInfo::GetUpdatesSource& source,
+    const syncable::ModelTypeSet& types_to_download,
+    const browser_sync::ModelSafeRoutingInfo& routing_info,
+    KeystoreKeyStatus keystore_key_status,
+    const base::Closure& ready_task)
+    : source(source),
+      types_to_download(types_to_download),
+      routing_info(routing_info),
+      keystore_key_status(keystore_key_status),
+      ready_task(ready_task) {
+  DCHECK(!ready_task.is_null());
+}
+ConfigurationParams::~ConfigurationParams() {}
+
 SyncScheduler::DelayProvider::DelayProvider() {}
 SyncScheduler::DelayProvider::~DelayProvider() {}
 
@@ -99,12 +117,16 @@ SyncScheduler::SyncSessionJob::~SyncSessionJob() {}
 
 SyncScheduler::SyncSessionJob::SyncSessionJob(SyncSessionJobPurpose purpose,
     base::TimeTicks start,
-    linked_ptr<sessions::SyncSession> session, bool is_canary_job,
-    const tracked_objects::Location& from_here) : purpose(purpose),
-        scheduled_start(start),
-        session(session),
-        is_canary_job(is_canary_job),
-        from_here(from_here) {
+    linked_ptr<sessions::SyncSession> session,
+    bool is_canary_job,
+    ConfigurationParams config_params,
+    const tracked_objects::Location& from_here)
+    : purpose(purpose),
+      scheduled_start(start),
+      session(session),
+      is_canary_job(is_canary_job),
+      config_params(config_params),
+      from_here(from_here) {
 }
 
 const char* SyncScheduler::SyncSessionJob::GetPurposeString(
@@ -247,7 +269,7 @@ void SyncScheduler::UpdateServerConnectionManagerStatus(
   connection_code_ = code;
 }
 
-void SyncScheduler::Start(Mode mode, const base::Closure& callback) {
+void SyncScheduler::Start(Mode mode) {
   DCHECK_EQ(MessageLoop::current(), sync_loop_);
   std::string thread_name = MessageLoop::current()->thread_name();
   if (thread_name.empty())
@@ -264,8 +286,6 @@ void SyncScheduler::Start(Mode mode, const base::Closure& callback) {
   Mode old_mode = mode_;
   mode_ = mode;
   AdjustPolling(NULL);  // Will kick start poll timer if needed.
-  if (!callback.is_null())
-    callback.Run();
 
   if (old_mode != mode_) {
     // We just changed our mode. See if there are any pending jobs that we could
@@ -284,6 +304,112 @@ void SyncScheduler::SendInitialSnapshot() {
   session_context_->NotifyListeners(event);
 }
 
+namespace {
+
+// Helper to extract the routing info and workers corresponding to types in
+// |types| from |current_routes| and |current_workers|.
+void BuildModelSafeParams(
+    const ModelTypeSet& types_to_download,
+    const ModelSafeRoutingInfo& current_routes,
+    const std::vector<ModelSafeWorker*>& current_workers,
+    ModelSafeRoutingInfo* result_routes,
+    std::vector<ModelSafeWorker*>* result_workers) {
+  std::set<ModelSafeGroup> active_groups;
+  active_groups.insert(GROUP_PASSIVE);
+  for (ModelTypeSet::Iterator iter = types_to_download.First(); iter.Good();
+       iter.Inc()) {
+    syncable::ModelType type = iter.Get();
+    ModelSafeRoutingInfo::const_iterator route = current_routes.find(type);
+    DCHECK(route != current_routes.end());
+    ModelSafeGroup group = route->second;
+    (*result_routes)[type] = group;
+    active_groups.insert(group);
+  }
+
+  for(std::vector<ModelSafeWorker*>::const_iterator iter =
+          current_workers.begin(); iter != current_workers.end(); ++iter) {
+    if (active_groups.count((*iter)->GetModelSafeGroup()) > 0)
+      result_workers->push_back(*iter);
+  }
+}
+
+}  // namespace.
+
+bool SyncScheduler::ScheduleConfiguration(const ConfigurationParams& params) {
+  DCHECK_EQ(MessageLoop::current(), sync_loop_);
+  DCHECK(IsConfigRelatedUpdateSourceValue(params.source));
+  DCHECK_EQ(CONFIGURATION_MODE, mode_);
+  DCHECK(!params.ready_task.is_null());
+  SDVLOG(2) << "Reconfiguring syncer.";
+
+  // Only one configuration is allowed at a time. Verify we're not waiting
+  // for a pending configure job.
+  DCHECK(!wait_interval_.get() || !wait_interval_->pending_configure_job.get());
+
+  // TODO(sync): now that ModelChanging commands only use those workers within
+  // the routing info, we don't really need |restricted_workers|. Remove it.
+  // crbug.com/133030
+  browser_sync::ModelSafeRoutingInfo restricted_routes;
+  std::vector<ModelSafeWorker*> restricted_workers;
+  BuildModelSafeParams(params.types_to_download,
+                       params.routing_info,
+                       session_context_->workers(),
+                       &restricted_routes,
+                       &restricted_workers);
+  session_context_->set_routing_info(params.routing_info);
+
+  // We rely on this not failing, so don't need to worry about checking for
+  // success. In addition, this will be removed as part of crbug.com/131433.
+  SyncSessionJob cleanup_job(
+      SyncSessionJob::CLEANUP_DISABLED_TYPES,
+      TimeTicks::Now(),
+      make_linked_ptr(CreateSyncSession(SyncSourceInfo())),
+      false,
+      ConfigurationParams(),
+      FROM_HERE);
+  DoSyncSessionJob(cleanup_job);
+
+  if (params.keystore_key_status == ConfigurationParams::KEYSTORE_KEY_NEEDED) {
+    // TODO(zea): implement in such a way that we can handle failures and the
+    // subsequent retrys the scheduler might perform. See crbug.com/129665.
+    NOTIMPLEMENTED();
+  }
+
+  // Only reconfigure if we have types to download.
+  if (!params.types_to_download.Empty()) {
+    DCHECK(!restricted_routes.empty());
+    linked_ptr<SyncSession> session(new SyncSession(
+        session_context_,
+        this,
+        SyncSourceInfo(params.source,
+                       syncable::ModelTypePayloadMapFromRoutingInfo(
+                           restricted_routes,
+                           std::string())),
+        restricted_routes,
+        restricted_workers));
+    SyncSessionJob job(SyncSessionJob::CONFIGURATION,
+                       TimeTicks::Now(),
+                       session,
+                       false,
+                       params,
+                       FROM_HERE);
+    DoSyncSessionJob(job);
+
+    // If we failed, the job would have been saved as the pending configure
+    // job and a wait interval would have been set.
+    if (!session->Succeeded()) {
+      DCHECK(wait_interval_.get() &&
+             wait_interval_->pending_configure_job.get());
+      return false;
+    }
+  } else {
+    SDVLOG(2) << "No change in routing info, calling ready task directly.";
+    params.ready_task.Run();
+  }
+
+  return true;
+}
+
 SyncScheduler::JobProcessDecision SyncScheduler::DecideWhileInWaitInterval(
     const SyncSessionJob& job) {
   DCHECK_EQ(MessageLoop::current(), sync_loop_);
@@ -382,7 +508,8 @@ void SyncScheduler::InitOrCoalescePendingJob(const SyncSessionJob& job) {
         s->delegate(), s->source(), s->routing_info(), s->workers()));
 
     SyncSessionJob new_job(SyncSessionJob::NUDGE, job.scheduled_start,
-        make_linked_ptr(session.release()), false, job.from_here);
+        make_linked_ptr(session.release()), false,
+        ConfigurationParams(), job.from_here);
     pending_nudge_.reset(new SyncSessionJob(new_job));
 
     return;
@@ -428,11 +555,17 @@ void SyncScheduler::SaveJob(const SyncSessionJob& job) {
     DCHECK(wait_interval_.get());
     DCHECK(mode_ == CONFIGURATION_MODE);
 
+    // Config params should always get set.
+    DCHECK(!job.config_params.ready_task.is_null());
     SyncSession* old = job.session.get();
     SyncSession* s(new SyncSession(session_context_, this, old->source(),
                                    old->routing_info(), old->workers()));
-    SyncSessionJob new_job(job.purpose, TimeTicks::Now(),
-                           make_linked_ptr(s), false, job.from_here);
+    SyncSessionJob new_job(job.purpose,
+                           TimeTicks::Now(),
+                           make_linked_ptr(s),
+                           false,
+                           job.config_params,
+                           job.from_here);
     wait_interval_->pending_configure_job.reset(new SyncSessionJob(new_job));
   } // drop the rest.
   // TODO(sync): Is it okay to drop the rest?  It's weird that
@@ -451,23 +584,16 @@ struct ModelSafeWorkerGroupIs {
 
 void SyncScheduler::ClearUserData() {
   DCHECK_EQ(MessageLoop::current(), sync_loop_);
-  SyncSessionJob job(SyncSessionJob::CLEAR_USER_DATA, TimeTicks::Now(),
+  SyncSessionJob job(SyncSessionJob::CLEAR_USER_DATA,
+                     TimeTicks::Now(),
                      make_linked_ptr(CreateSyncSession(SyncSourceInfo())),
                      false,
+                     ConfigurationParams(),
                      FROM_HERE);
 
   DoSyncSessionJob(job);
 }
 
-void SyncScheduler::CleanupDisabledTypes() {
-  DCHECK_EQ(MessageLoop::current(), sync_loop_);
-  SyncSessionJob job(SyncSessionJob::CLEANUP_DISABLED_TYPES, TimeTicks::Now(),
-                     make_linked_ptr(CreateSyncSession(SyncSourceInfo())),
-                     false,
-                     FROM_HERE);
-  DoSyncSessionJob(job);
-}
-
 void SyncScheduler::ScheduleNudgeAsync(
     const TimeDelta& delay,
     NudgeSource source, ModelTypeSet types,
@@ -525,7 +651,7 @@ void SyncScheduler::ScheduleNudgeImpl(
   SyncSession* session(CreateSyncSession(info));
   SyncSessionJob job(SyncSessionJob::NUDGE, TimeTicks::Now() + delay,
                      make_linked_ptr(session), is_canary_job,
-                     nudge_location);
+                     ConfigurationParams(), nudge_location);
 
   session = NULL;
   if (!ShouldRunJob(job))
@@ -556,77 +682,6 @@ void SyncScheduler::ScheduleNudgeImpl(
   ScheduleSyncSessionJob(job);
 }
 
-// Helper to extract the routing info and workers corresponding to types in
-// |types| from |current_routes| and |current_workers|.
-void GetModelSafeParamsForTypes(ModelTypeSet types,
-    const ModelSafeRoutingInfo& current_routes,
-    const std::vector<ModelSafeWorker*>& current_workers,
-    ModelSafeRoutingInfo* result_routes,
-    std::vector<ModelSafeWorker*>* result_workers) {
-  bool passive_group_added = false;
-
-  typedef std::vector<ModelSafeWorker*>::const_iterator iter;
-  for (ModelTypeSet::Iterator it = types.First();
-       it.Good(); it.Inc()) {
-    const syncable::ModelType t = it.Get();
-    ModelSafeRoutingInfo::const_iterator route = current_routes.find(t);
-    DCHECK(route != current_routes.end());
-    ModelSafeGroup group = route->second;
-
-    (*result_routes)[t] = group;
-    iter w_tmp_it = std::find_if(current_workers.begin(), current_workers.end(),
-                                 ModelSafeWorkerGroupIs(group));
-    if (w_tmp_it != current_workers.end()) {
-      iter result_workers_it = std::find_if(
-          result_workers->begin(), result_workers->end(),
-          ModelSafeWorkerGroupIs(group));
-      if (result_workers_it == result_workers->end())
-        result_workers->push_back(*w_tmp_it);
-
-      if (group == GROUP_PASSIVE)
-        passive_group_added = true;
-    } else {
-        NOTREACHED();
-    }
-  }
-
-  // Always add group passive.
-  if (passive_group_added == false) {
-    iter it = std::find_if(current_workers.begin(), current_workers.end(),
-                           ModelSafeWorkerGroupIs(GROUP_PASSIVE));
-    if (it != current_workers.end())
-      result_workers->push_back(*it);
-    else
-      NOTREACHED();
-  }
-}
-
-void SyncScheduler::ScheduleConfiguration(
-    ModelTypeSet types,
-    GetUpdatesCallerInfo::GetUpdatesSource source) {
-  DCHECK_EQ(MessageLoop::current(), sync_loop_);
-  DCHECK(IsConfigRelatedUpdateSourceValue(source));
-  SDVLOG(2) << "Scheduling a config";
-
-  ModelSafeRoutingInfo routes;
-  std::vector<ModelSafeWorker*> workers;
-  GetModelSafeParamsForTypes(types,
-                             session_context_->routing_info(),
-                             session_context_->workers(),
-                             &routes, &workers);
-
-  SyncSession* session = new SyncSession(session_context_, this,
-      SyncSourceInfo(source,
-                     syncable::ModelTypePayloadMapFromRoutingInfo(
-                         routes, std::string())),
-      routes, workers);
-  SyncSessionJob job(SyncSessionJob::CONFIGURATION, TimeTicks::Now(),
-                     make_linked_ptr(session),
-                     false,
-                     FROM_HERE);
-  DoSyncSessionJob(job);
-}
-
 const char* SyncScheduler::GetModeString(SyncScheduler::Mode mode) {
   switch (mode) {
     ENUM_CASE(CONFIGURATION_MODE);
@@ -829,6 +884,11 @@ void SyncScheduler::FinishSyncSessionJob(const SyncSessionJob& job) {
     // here; see DCHECKs in SaveJob().  (See http://crbug.com/90868.)
     SaveJob(job);
     return;  // Nothing to do.
+  } else if (job.session->Succeeded() &&
+             !job.config_params.ready_task.is_null()) {
+    // If this was a configuration job with a ready task, invoke it now that
+    // we finished successfully.
+    job.config_params.ready_task.Run();
   }
 
   SDVLOG(2) << "Updating the next polling time after SyncMain";
@@ -931,11 +991,15 @@ void SyncScheduler::HandleContinuationError(
   wait_interval_.reset(new WaitInterval(WaitInterval::EXPONENTIAL_BACKOFF,
                                         length));
   if (old_job.purpose == SyncSessionJob::CONFIGURATION) {
+    SDVLOG(2) << "Configuration did not succeed, scheduling retry.";
+    // Config params should always get set.
+    DCHECK(!old_job.config_params.ready_task.is_null());
     SyncSession* old = old_job.session.get();
     SyncSession* s(new SyncSession(session_context_, this,
         old->source(), old->routing_info(), old->workers()));
     SyncSessionJob job(old_job.purpose, TimeTicks::Now() + length,
-                        make_linked_ptr(s), false, FROM_HERE);
+                       make_linked_ptr(s), false, old_job.config_params,
+                       FROM_HERE);
     wait_interval_->pending_configure_job.reset(new SyncSessionJob(job));
   } else {
     // We are not in configuration mode. So wait_interval's pending job
@@ -1057,6 +1121,7 @@ void SyncScheduler::PollTimerCallback() {
   SyncSessionJob job(SyncSessionJob::POLL, TimeTicks::Now(),
                      make_linked_ptr(s),
                      false,
+                     ConfigurationParams(),
                      FROM_HERE);
 
   ScheduleSyncSessionJob(job);
diff --git a/sync/engine/sync_scheduler.h b/sync/engine/sync_scheduler.h
index d32ee25..8ebd2aa 100644
--- a/sync/engine/sync_scheduler.h
+++ b/sync/engine/sync_scheduler.h
@@ -37,6 +37,32 @@ namespace browser_sync {
 
 struct ServerConnectionEvent;
 
+struct ConfigurationParams {
+  enum KeystoreKeyStatus {
+    KEYSTORE_KEY_UNNECESSARY,
+    KEYSTORE_KEY_NEEDED
+  };
+  ConfigurationParams();
+  ConfigurationParams(
+      const sync_pb::GetUpdatesCallerInfo::GetUpdatesSource& source,
+      const syncable::ModelTypeSet& types_to_download,
+      const browser_sync::ModelSafeRoutingInfo& routing_info,
+      KeystoreKeyStatus keystore_key_status,
+      const base::Closure& ready_task);
+  ~ConfigurationParams();
+
+  // Source for the configuration.
+  sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source;
+  // The types that should be downloaded.
+  syncable::ModelTypeSet types_to_download;
+  // The new routing info (superset of types to be downloaded).
+  ModelSafeRoutingInfo routing_info;
+  // Whether we need to perform a GetKey command.
+  KeystoreKeyStatus keystore_key_status;
+  // Callback to invoke on configuration completion.
+  base::Closure ready_task;
+};
+
 class SyncScheduler : public sessions::SyncSession::Delegate {
  public:
   enum Mode {
@@ -63,10 +89,15 @@ class SyncScheduler : public sessions::SyncSession::Delegate {
 
   // Start the scheduler with the given mode.  If the scheduler is
   // already started, switch to the given mode, although some
-  // scheduled tasks from the old mode may still run.  If non-NULL,
-  // |callback| will be invoked when the mode has been changed to
-  // |mode|.  Takes ownership of |callback|.
-  void Start(Mode mode, const base::Closure& callback);
+  // scheduled tasks from the old mode may still run.
+  virtual void Start(Mode mode);
+
+  // Schedules the configuration task specified by |params|. Returns true if
+  // the configuration task executed immediately, false if it had to be
+  // scheduled for a later attempt. |params.ready_task| is invoked whenever the
+  // configuration task executes.
+  // Note: must already be in CONFIGURATION mode.
+  virtual bool ScheduleConfiguration(const ConfigurationParams& params);
 
   // Request that any running syncer task stop as soon as possible and
   // cancel all scheduled tasks. This function can be called from any thread,
@@ -86,14 +117,6 @@ class SyncScheduler : public sessions::SyncSession::Delegate {
       const syncable::ModelTypePayloadMap& types_with_payloads,
       const tracked_objects::Location& nudge_location);
 
-  // Schedule a configuration cycle. May execute immediately or at a later time
-  // (depending on backoff/throttle state).
-  // Note: The source argument of this function must come from the subset of
-  // GetUpdatesCallerInfo values related to configurations.
-  void ScheduleConfiguration(
-      syncable::ModelTypeSet types,
-      sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source);
-
   // TODO(tim): remove this. crbug.com/131336
   void ClearUserData();
 
@@ -164,6 +187,7 @@ class SyncScheduler : public sessions::SyncSession::Delegate {
     SyncSessionJob();
     SyncSessionJob(SyncSessionJobPurpose purpose, base::TimeTicks start,
         linked_ptr<sessions::SyncSession> session, bool is_canary_job,
+        ConfigurationParams config_params,
         const tracked_objects::Location& nudge_location);
     ~SyncSessionJob();
     static const char* GetPurposeString(SyncSessionJobPurpose purpose);
@@ -172,6 +196,7 @@ class SyncScheduler : public sessions::SyncSession::Delegate {
     base::TimeTicks scheduled_start;
     linked_ptr<sessions::SyncSession> session;
     bool is_canary_job;
+    ConfigurationParams config_params;
 
     // This is the location the job came from.  Used for debugging.
     // In case of multiple nudges getting coalesced this stores the
diff --git a/sync/engine/sync_scheduler_unittest.cc b/sync/engine/sync_scheduler_unittest.cc
index a6d8059..7aa30ab 100644
--- a/sync/engine/sync_scheduler_unittest.cc
+++ b/sync/engine/sync_scheduler_unittest.cc
@@ -12,6 +12,7 @@
 #include "sync/engine/syncer.h"
 #include "sync/engine/throttled_data_type_tracker.h"
 #include "sync/sessions/test_util.h"
+#include "sync/test/callback_counter.h"
 #include "sync/test/engine/fake_model_worker.h"
 #include "sync/test/engine/mock_connection_manager.h"
 #include "sync/test/engine/test_directory_setter_upper.h"
@@ -27,6 +28,7 @@ using testing::DoAll;
 using testing::Eq;
 using testing::Invoke;
 using testing::Mock;
+using testing::Not;
 using testing::Return;
 using testing::WithArg;
 
@@ -69,6 +71,14 @@ void PumpLoop() {
   RunLoop();
 }
 
+ModelSafeRoutingInfo TypesToRoutingInfo(const ModelTypeSet& types) {
+  ModelSafeRoutingInfo routes;
+  for (ModelTypeSet::Iterator iter = types.First(); iter.Good(); iter.Inc()) {
+    routes[iter.Get()] = GROUP_PASSIVE;
+  }
+  return routes;
+}
+
 // Convenient to use in tests wishing to analyze SyncShare calls over time.
 static const size_t kMinNumSamples = 5;
 class SyncSchedulerTest : public testing::Test {
@@ -152,7 +162,7 @@ class SyncSchedulerTest : public testing::Test {
   }
 
   void StartSyncScheduler(SyncScheduler::Mode mode) {
-    scheduler()->Start(mode, base::Closure());
+    scheduler()->Start(mode);
   }
 
   // This stops the scheduler synchronously.
@@ -291,14 +301,23 @@ TEST_F(SyncSchedulerTest, Config) {
   SyncShareRecords records;
   const ModelTypeSet model_types(syncable::BOOKMARKS);
 
-  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
+  EXPECT_CALL(*syncer(),
+              SyncShare(_,_,_))
+      .WillOnce(Invoke(sessions::test_util::SimulateSuccess))
       .WillOnce(DoAll(Invoke(sessions::test_util::SimulateSuccess),
                       WithArg<0>(RecordSyncShare(&records))));
 
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
-  scheduler()->ScheduleConfiguration(
-      model_types, GetUpdatesCallerInfo::RECONFIGURATION);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      model_types,
+      TypesToRoutingInfo(model_types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_TRUE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(1, counter.times_called());
 
   ASSERT_EQ(1U, records.snapshots.size());
   EXPECT_TRUE(CompareModelTypeSetToModelTypePayloadMap(model_types,
@@ -315,7 +334,9 @@ TEST_F(SyncSchedulerTest, ConfigWithBackingOff) {
   SyncShareRecords records;
   const ModelTypeSet model_types(syncable::BOOKMARKS);
 
-  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
+  EXPECT_CALL(*syncer(),
+              SyncShare(_,_,_))
+      .WillOnce(Invoke(sessions::test_util::SimulateSuccess))
       .WillOnce(DoAll(Invoke(sessions::test_util::SimulateCommitFailed),
                       WithArg<0>(RecordSyncShare(&records))))
       .WillOnce(DoAll(Invoke(sessions::test_util::SimulateSuccess),
@@ -324,61 +345,27 @@ TEST_F(SyncSchedulerTest, ConfigWithBackingOff) {
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
   ASSERT_EQ(0U, records.snapshots.size());
-  scheduler()->ScheduleConfiguration(
-      model_types, GetUpdatesCallerInfo::RECONFIGURATION);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      model_types,
+      TypesToRoutingInfo(model_types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_FALSE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(0, counter.times_called());
 
   ASSERT_EQ(1U, records.snapshots.size());
   RunLoop();
 
   ASSERT_EQ(2U, records.snapshots.size());
+  ASSERT_EQ(1, counter.times_called());
   EXPECT_TRUE(CompareModelTypeSetToModelTypePayloadMap(model_types,
       records.snapshots[1].source().types));
   EXPECT_EQ(GetUpdatesCallerInfo::RECONFIGURATION,
             records.snapshots[1].source().updates_source);
 }
 
-// Issue 2 config commands. Second one right after the first has failed
-// and make sure LATEST is executed.
-TEST_F(SyncSchedulerTest, MultipleConfigWithBackingOff) {
-  const ModelTypeSet
-      model_types1(syncable::BOOKMARKS),
-      model_types2(syncable::AUTOFILL);
-  UseMockDelayProvider();
-  EXPECT_CALL(*delay(), GetDelay(_))
-      .WillRepeatedly(Return(TimeDelta::FromMilliseconds(30)));
-  SyncShareRecords records;
-
-  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
-      .WillOnce(DoAll(Invoke(sessions::test_util::SimulateCommitFailed),
-                      WithArg<0>(RecordSyncShare(&records))))
-      .WillOnce(DoAll(Invoke(sessions::test_util::SimulateCommitFailed),
-                      WithArg<0>(RecordSyncShare(&records))))
-      .WillOnce(DoAll(Invoke(sessions::test_util::SimulateSuccess),
-                      WithArg<0>(RecordSyncShare(&records))));
-
-  StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
-
-  ASSERT_EQ(0U, records.snapshots.size());
-  scheduler()->ScheduleConfiguration(
-      model_types1, GetUpdatesCallerInfo::RECONFIGURATION);
-
-  ASSERT_EQ(1U, records.snapshots.size());
-  scheduler()->ScheduleConfiguration(
-      model_types2, GetUpdatesCallerInfo::RECONFIGURATION);
-
-  // A canary job gets posted when we go into exponential backoff.
-  RunLoop();
-
-  ASSERT_EQ(2U, records.snapshots.size());
-  RunLoop();
-
-  ASSERT_EQ(3U, records.snapshots.size());
-  EXPECT_TRUE(CompareModelTypeSetToModelTypePayloadMap(model_types2,
-      records.snapshots[2].source().types));
-  EXPECT_EQ(GetUpdatesCallerInfo::RECONFIGURATION,
-            records.snapshots[2].source().updates_source);
-}
-
 // Issue a nudge when the config has failed. Make sure both the config and
 // nudge are executed.
 TEST_F(SyncSchedulerTest, NudgeWithConfigWithBackingOff) {
@@ -401,19 +388,28 @@ TEST_F(SyncSchedulerTest, NudgeWithConfigWithBackingOff) {
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
   ASSERT_EQ(0U, records.snapshots.size());
-  scheduler()->ScheduleConfiguration(
-      model_types, GetUpdatesCallerInfo::RECONFIGURATION);
-
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      model_types,
+      TypesToRoutingInfo(model_types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_FALSE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(0, counter.times_called());
   ASSERT_EQ(1U, records.snapshots.size());
+
   scheduler()->ScheduleNudgeAsync(
       zero(), NUDGE_SOURCE_LOCAL, model_types, FROM_HERE);
   RunLoop();
-
   ASSERT_EQ(2U, records.snapshots.size());
+  ASSERT_EQ(0, counter.times_called());
+
   RunLoop();
+  ASSERT_EQ(3U, records.snapshots.size());
+  ASSERT_EQ(1, counter.times_called());
 
   // Now change the mode so nudge can execute.
-  ASSERT_EQ(3U, records.snapshots.size());
   StartSyncScheduler(SyncScheduler::NORMAL_MODE);
 
   ASSERT_EQ(4U, records.snapshots.size());
@@ -718,13 +714,19 @@ TEST_F(SyncSchedulerTest, HasMoreToSyncThenFails) {
   EXPECT_TRUE(RunAndGetBackoff());
 }
 
-// Test that no syncing occurs when throttled.
+// Test that no syncing occurs when throttled (although CleanupDisabledTypes
+// is allowed).
 TEST_F(SyncSchedulerTest, ThrottlingDoesThrottle) {
   const ModelTypeSet types(syncable::BOOKMARKS);
   TimeDelta poll(TimeDelta::FromMilliseconds(5));
   TimeDelta throttle(TimeDelta::FromMinutes(10));
   scheduler()->OnReceivedLongPollIntervalUpdate(poll);
-  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
+
+  EXPECT_CALL(*syncer(),
+              SyncShare(_, CLEANUP_DISABLED_TYPES, CLEANUP_DISABLED_TYPES))
+      .WillOnce(Invoke(sessions::test_util::SimulateSuccess));
+  EXPECT_CALL(*syncer(), SyncShare(_,Not(CLEANUP_DISABLED_TYPES),
+                                     Not(CLEANUP_DISABLED_TYPES)))
       .WillOnce(WithArg<0>(sessions::test_util::SimulateThrottled(throttle)))
       .WillRepeatedly(AddFailureAndQuitLoopNow());
 
@@ -736,8 +738,15 @@ TEST_F(SyncSchedulerTest, ThrottlingDoesThrottle) {
 
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
-  scheduler()->ScheduleConfiguration(
-      types, GetUpdatesCallerInfo::RECONFIGURATION);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      types,
+      TypesToRoutingInfo(types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_FALSE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(0, counter.times_called());
 }
 
 TEST_F(SyncSchedulerTest, ThrottlingExpires) {
@@ -770,6 +779,7 @@ TEST_F(SyncSchedulerTest, ConfigurationMode) {
   SyncShareRecords records;
   scheduler()->OnReceivedLongPollIntervalUpdate(poll);
   EXPECT_CALL(*syncer(), SyncShare(_,_,_))
+      .WillOnce(Invoke(sessions::test_util::SimulateSuccess))
       .WillOnce(DoAll(Invoke(sessions::test_util::SimulateSuccess),
                       WithArg<0>(RecordSyncShare(&records))));
 
@@ -783,8 +793,15 @@ TEST_F(SyncSchedulerTest, ConfigurationMode) {
 
   const ModelTypeSet config_types(syncable::BOOKMARKS);
 
-  scheduler()->ScheduleConfiguration(
-      config_types, GetUpdatesCallerInfo::RECONFIGURATION);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      config_types,
+      TypesToRoutingInfo(config_types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_TRUE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(1, counter.times_called());
 
   ASSERT_EQ(1U, records.snapshots.size());
   EXPECT_TRUE(CompareModelTypeSetToModelTypePayloadMap(config_types,
@@ -853,7 +870,7 @@ TEST_F(SyncSchedulerTest, BackoffDropsJobs) {
   scheduler()->OnReceivedLongPollIntervalUpdate(poll);
   UseMockDelayProvider();
 
-  EXPECT_CALL(*syncer(), SyncShare(_,_,_)).Times(1)
+  EXPECT_CALL(*syncer(), SyncShare(_,_,_))
       .WillRepeatedly(DoAll(Invoke(sessions::test_util::SimulateCommitFailed),
                             RecordSyncShareMultiple(&r, 1U)));
   EXPECT_CALL(*delay(), GetDelay(_)).
@@ -895,9 +912,15 @@ TEST_F(SyncSchedulerTest, BackoffDropsJobs) {
 
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
-  scheduler()->CleanupDisabledTypes();
-  scheduler()->ScheduleConfiguration(
-      types, GetUpdatesCallerInfo::RECONFIGURATION);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      types,
+      TypesToRoutingInfo(types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_FALSE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(0, counter.times_called());
 
   StartSyncScheduler(SyncScheduler::NORMAL_MODE);
 
@@ -1066,28 +1089,49 @@ TEST_F(SyncSchedulerTest, SyncerSteps) {
   StopSyncScheduler();
   Mock::VerifyAndClearExpectations(syncer());
 
-  // Configuration.
+  // Configuration (always includes a cleanup disabled types).
+  EXPECT_CALL(*syncer(),
+              SyncShare(_, CLEANUP_DISABLED_TYPES, CLEANUP_DISABLED_TYPES))
+      .WillOnce(Invoke(sessions::test_util::SimulateSuccess));
   EXPECT_CALL(*syncer(), SyncShare(_, DOWNLOAD_UPDATES, APPLY_UPDATES))
       .WillOnce(Invoke(sessions::test_util::SimulateSuccess));
   StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
-  scheduler()->ScheduleConfiguration(
-      ModelTypeSet(), GetUpdatesCallerInfo::RECONFIGURATION);
-
+  syncable::ModelTypeSet model_types(syncable::BOOKMARKS);
+  CallbackCounter counter;
+  ConfigurationParams params(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      model_types,
+      TypesToRoutingInfo(model_types),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter)));
+  ASSERT_TRUE(scheduler()->ScheduleConfiguration(params));
+  ASSERT_EQ(1, counter.times_called());
+  // Runs directly so no need to pump the loop.
   StopSyncScheduler();
   Mock::VerifyAndClearExpectations(syncer());
 
-  // Cleanup disabled types.
+  // Cleanup disabled types. Because no types are being configured, we just
+  // perform the cleanup.
   EXPECT_CALL(*syncer(),
-              SyncShare(_, CLEANUP_DISABLED_TYPES, CLEANUP_DISABLED_TYPES))
-      .WillOnce(Invoke(sessions::test_util::SimulateSuccess));
-  StartSyncScheduler(SyncScheduler::NORMAL_MODE);
-
-  scheduler()->CleanupDisabledTypes();
+              SyncShare(_, CLEANUP_DISABLED_TYPES, CLEANUP_DISABLED_TYPES)).
+      WillOnce(Invoke(sessions::test_util::SimulateSuccess));
+  StartSyncScheduler(SyncScheduler::CONFIGURATION_MODE);
 
+  CallbackCounter counter2;
+  ConfigurationParams params2(
+      GetUpdatesCallerInfo::RECONFIGURATION,
+      ModelTypeSet(),
+      ModelSafeRoutingInfo(),
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY,
+      base::Bind(&CallbackCounter::Callback, base::Unretained(&counter2)));
+  ASSERT_TRUE(scheduler()->ScheduleConfiguration(params2));
+  ASSERT_EQ(1, counter2.times_called());
   StopSyncScheduler();
   Mock::VerifyAndClearExpectations(syncer());
 
+  StartSyncScheduler(SyncScheduler::NORMAL_MODE);
+
   // Poll.
   EXPECT_CALL(*syncer(), SyncShare(_, SYNCER_BEGIN, SYNCER_END))
       .Times(AtLeast(1))
diff --git a/sync/engine/sync_scheduler_whitebox_unittest.cc b/sync/engine/sync_scheduler_whitebox_unittest.cc
index 34ff7d9..390a6cd 100644
--- a/sync/engine/sync_scheduler_whitebox_unittest.cc
+++ b/sync/engine/sync_scheduler_whitebox_unittest.cc
@@ -107,6 +107,7 @@ class SyncSchedulerWhiteboxTest : public testing::Test {
     SyncScheduler::SyncSessionJob job(purpose, TimeTicks::Now(),
          make_linked_ptr(s),
          false,
+         ConfigurationParams(),
          FROM_HERE);
     return DecideOnJob(job);
   }
@@ -160,6 +161,7 @@ TEST_F(SyncSchedulerWhiteboxTest, SaveNudgeWhileTypeThrottled) {
                                     TimeTicks::Now(),
                                     make_linked_ptr(s),
                                     false,
+                                    ConfigurationParams(),
                                     FROM_HERE);
 
   SyncScheduler::JobProcessDecision decision = DecideOnJob(job);
diff --git a/sync/internal_api/sync_manager.cc b/sync/internal_api/sync_manager.cc
index 8a2ff70..4cb5127 100644
--- a/sync/internal_api/sync_manager.cc
+++ b/sync/internal_api/sync_manager.cc
@@ -59,6 +59,7 @@
 
 using base::TimeDelta;
 using browser_sync::AllStatus;
+using browser_sync::ConfigurationParams;
 using browser_sync::Cryptographer;
 using browser_sync::Encryptor;
 using browser_sync::JsArgList;
@@ -397,6 +398,8 @@ class SyncManager::SyncInternal
       const std::string& name, const JsArgList& args,
       const WeakHandle<JsReplyHandler>& reply_handler) OVERRIDE;
 
+  void SetSyncSchedulerForTest(scoped_ptr<SyncScheduler> scheduler);
+
  private:
   struct NotificationInfo {
     int total_count;
@@ -816,46 +819,44 @@ bool SyncManager::IsUsingExplicitPassphrase() {
   return data_ && data_->IsUsingExplicitPassphrase();
 }
 
-void SyncManager::RequestCleanupDisabledTypes(
-    const browser_sync::ModelSafeRoutingInfo& routing_info) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  if (data_->scheduler()) {
-    data_->session_context()->set_routing_info(routing_info);
-    data_->scheduler()->CleanupDisabledTypes();
-  }
-}
-
 void SyncManager::RequestClearServerData() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (data_->scheduler())
     data_->scheduler()->ClearUserData();
 }
 
-void SyncManager::RequestConfig(
-    const browser_sync::ModelSafeRoutingInfo& routing_info,
-    const ModelTypeSet& types, ConfigureReason reason) {
+void SyncManager::ConfigureSyncer(
+    ConfigureReason reason,
+    const syncable::ModelTypeSet& types_to_config,
+    const browser_sync::ModelSafeRoutingInfo& new_routing_info,
+    const base::Closure& ready_task,
+    const base::Closure& retry_task) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  if (!data_->scheduler()) {
-    LOG(INFO)
-        << "SyncManager::RequestConfig: bailing out because scheduler is "
-        << "null";
-    return;
-  }
-  StartConfigurationMode(base::Closure());
-  data_->session_context()->set_routing_info(routing_info);
-  data_->scheduler()->ScheduleConfiguration(types, GetSourceFromReason(reason));
-}
+  DCHECK(!ready_task.is_null());
+  DCHECK(!retry_task.is_null());
+
+  // TODO(zea): set this based on whether cryptographer has keystore
+  // encryption key or not (requires opening a transaction). crbug.com/129665.
+  ConfigurationParams::KeystoreKeyStatus keystore_key_status =
+      ConfigurationParams::KEYSTORE_KEY_UNNECESSARY;
+
+  ConfigurationParams params(GetSourceFromReason(reason),
+                             types_to_config,
+                             new_routing_info,
+                             keystore_key_status,
+                             ready_task);
 
-void SyncManager::StartConfigurationMode(const base::Closure& callback) {
-  DCHECK(thread_checker_.CalledOnValidThread());
   if (!data_->scheduler()) {
     LOG(INFO)
-        << "SyncManager::StartConfigurationMode: could not start "
-        << "configuration mode because because scheduler is null";
+        << "SyncManager::ConfigureSyncer: could not configure because "
+        << "scheduler is null";
+    params.ready_task.Run();
     return;
   }
-  data_->scheduler()->Start(
-      browser_sync::SyncScheduler::CONFIGURATION_MODE, callback);
+
+  data_->scheduler()->Start(SyncScheduler::CONFIGURATION_MODE);
+  if (!data_->scheduler()->ScheduleConfiguration(params))
+    retry_task.Run();
 }
 
 bool SyncManager::SyncInternal::Init(
@@ -941,8 +942,7 @@ bool SyncManager::SyncInternal::Init(
 
   if (signed_in) {
     if (scheduler()) {
-      scheduler()->Start(
-          browser_sync::SyncScheduler::CONFIGURATION_MODE, base::Closure());
+      scheduler()->Start(SyncScheduler::CONFIGURATION_MODE);
     }
 
     initialized_ = true;
@@ -1116,9 +1116,13 @@ void SyncManager::SyncInternal::NotifyCryptographerState(
 void SyncManager::SyncInternal::StartSyncingNormally(
     const browser_sync::ModelSafeRoutingInfo& routing_info) {
   // Start the sync scheduler.
-  if (scheduler()) { // NULL during certain unittests.
+  if (scheduler()) {  // NULL during certain unittests.
+    // TODO(sync): We always want the newest set of routes when we switch back
+    // to normal mode. Figure out how to enforce set_routing_info is always
+    // appropriately set and that it's only modified when switching to normal
+    // mode.
     session_context()->set_routing_info(routing_info);
-    scheduler()->Start(SyncScheduler::NORMAL_MODE, base::Closure());
+    scheduler()->Start(SyncScheduler::NORMAL_MODE);
   }
 }
 
@@ -2353,6 +2357,11 @@ void SyncManager::SyncInternal::RemoveObserver(
   observers_.RemoveObserver(observer);
 }
 
+void SyncManager::SyncInternal::SetSyncSchedulerForTest(
+    scoped_ptr<SyncScheduler> sync_scheduler) {
+  scheduler_ = sync_scheduler.Pass();
+}
+
 SyncStatus SyncManager::GetDetailedStatus() const {
   return data_->GetStatus();
 }
@@ -2383,6 +2392,10 @@ TimeDelta SyncManager::GetNudgeDelayTimeDelta(
   return data_->GetNudgeDelayTimeDelta(model_type);
 }
 
+void SyncManager::SetSyncSchedulerForTest(scoped_ptr<SyncScheduler> scheduler) {
+  data_->SetSyncSchedulerForTest(scheduler.Pass());
+}
+
 syncable::ModelTypeSet SyncManager::GetEncryptedDataTypesForTest() const {
   ReadTransaction trans(FROM_HERE, GetUserShare());
   return GetEncryptedTypes(&trans);
diff --git a/sync/internal_api/sync_manager.h b/sync/internal_api/sync_manager.h
index 04594fd..04181fe 100644
--- a/sync/internal_api/sync_manager.h
+++ b/sync/internal_api/sync_manager.h
@@ -26,11 +26,13 @@
 #include "sync/util/weak_handle.h"
 
 namespace browser_sync {
+struct ConfigurationParams;
 class Encryptor;
 struct Experiments;
 class ExtensionsActivityMonitor;
 class JsBackend;
 class JsEventHandler;
+class SyncScheduler;
 
 namespace sessions {
 class SyncSessionSnapshot;
@@ -431,24 +433,24 @@ class SyncManager {
   // error to call this when we don't have pending keys.
   void SetDecryptionPassphrase(const std::string& passphrase);
 
-  // Puts the SyncScheduler into a mode where no normal nudge or poll traffic
-  // will occur, but calls to RequestConfig will be supported.  If |callback|
-  // is provided, it will be invoked (from the internal SyncScheduler) when
-  // the thread has changed to configuration mode.
-  void StartConfigurationMode(const base::Closure& callback);
-
-  // Switches the mode of operation to CONFIGURATION_MODE and
-  // schedules a config task to fetch updates for |types|.
-  void RequestConfig(const browser_sync::ModelSafeRoutingInfo& routing_info,
-                     const syncable::ModelTypeSet& types,
-                     sync_api::ConfigureReason reason);
-
-  void RequestCleanupDisabledTypes(
-      const browser_sync::ModelSafeRoutingInfo& routing_info);
-
   // Request a clearing of all data on the server
   void RequestClearServerData();
 
+  // Switches the mode of operation to CONFIGURATION_MODE and performs
+  // any configuration tasks needed as determined by the params. Once complete,
+  // syncer will remain in CONFIGURATION_MODE until StartSyncingNormally is
+  // called.
+  // |ready_task| is invoked when the configuration completes.
+  // |retry_task| is invoked if the configuration job could not immediately
+  //              execute. |ready_task| will still be called when it eventually
+  //              does finish.
+  void ConfigureSyncer(
+      ConfigureReason reason,
+      const syncable::ModelTypeSet& types_to_config,
+      const browser_sync::ModelSafeRoutingInfo& new_routing_info,
+      const base::Closure& ready_task,
+      const base::Closure& retry_task);
+
   // Adds a listener to be notified of sync events.
   // NOTE: It is OK (in fact, it's probably a good idea) to call this before
   // having received OnInitializationCompleted.
@@ -543,11 +545,17 @@ class SyncManager {
   static const FilePath::CharType kSyncDatabaseFilename[];
 
  private:
+  friend class SyncManagerTest;
   FRIEND_TEST_ALL_PREFIXES(SyncManagerTest, NudgeDelayTest);
 
   // For unit tests.
   base::TimeDelta GetNudgeDelayTimeDelta(const syncable::ModelType& model_type);
 
+  // Set the internal scheduler for testing purposes.
+  // TODO(sync): Use dependency injection instead. crbug.com/133061
+  void SetSyncSchedulerForTest(
+      scoped_ptr<browser_sync::SyncScheduler> scheduler);
+
   base::ThreadChecker thread_checker_;
 
   // An opaque pointer to the nested private class.
diff --git a/sync/internal_api/syncapi_unittest.cc b/sync/internal_api/syncapi_unittest.cc
index 991aed6..6380db3 100644
--- a/sync/internal_api/syncapi_unittest.cc
+++ b/sync/internal_api/syncapi_unittest.cc
@@ -24,6 +24,7 @@
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "sync/engine/nigori_util.h"
+#include "sync/engine/sync_scheduler.h"
 #include "sync/internal_api/change_record.h"
 #include "sync/internal_api/http_post_provider_factory.h"
 #include "sync/internal_api/http_post_provider_interface.h"
@@ -54,6 +55,7 @@
 #include "sync/sessions/sync_session.h"
 #include "sync/syncable/syncable.h"
 #include "sync/syncable/syncable_id.h"
+#include "sync/test/callback_counter.h"
 #include "sync/test/fake_encryptor.h"
 #include "sync/test/fake_extensions_activity_monitor.h"
 #include "sync/util/cryptographer.h"
@@ -64,6 +66,8 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 using base::ExpectDictStringValue;
+using browser_sync::CallbackCounter;
+using browser_sync::ConfigurationParams;
 using browser_sync::Cryptographer;
 using browser_sync::FakeEncryptor;
 using browser_sync::FakeExtensionsActivityMonitor;
@@ -80,6 +84,7 @@ using browser_sync::MockJsReplyHandler;
 using browser_sync::ModelSafeRoutingInfo;
 using browser_sync::ModelSafeWorker;
 using browser_sync::sessions::SyncSessionSnapshot;
+using browser_sync::SyncScheduler;
 using browser_sync::TestUnrecoverableErrorHandler;
 using browser_sync::WeakHandle;
 using syncable::IS_DEL;
@@ -92,8 +97,10 @@ using syncable::SPECIFICS;
 using testing::_;
 using testing::AnyNumber;
 using testing::AtLeast;
+using testing::DoAll;
 using testing::InSequence;
 using testing::Invoke;
+using testing::Return;
 using testing::SaveArg;
 using testing::StrictMock;
 
@@ -926,6 +933,10 @@ class SyncManagerTest : public testing::Test,
     return true;
   }
 
+  void SetScheduler(scoped_ptr<SyncScheduler> scheduler) {
+    sync_manager_.SetSyncSchedulerForTest(scheduler.Pass());
+  }
+
  private:
   // Needed by |sync_manager_|.
   MessageLoop message_loop_;
@@ -2507,4 +2518,82 @@ TEST_F(SyncManagerTest, SetPreviouslyEncryptedSpecifics) {
   }
 }
 
+namespace {
+
+class MockSyncScheduler : public SyncScheduler {
+ public:
+  MockSyncScheduler() : SyncScheduler("name", NULL, NULL) {}
+  virtual ~MockSyncScheduler() {}
+
+  MOCK_METHOD1(Start, void(SyncScheduler::Mode));
+  MOCK_METHOD1(ScheduleConfiguration, bool(const ConfigurationParams&));
+};
+
+}  // namespace
+
+// Test that the configuration params are properly created and sent to
+// ScheduleConfigure. No callback should be invoked.
+TEST_F(SyncManagerTest, BasicConfiguration) {
+  ConfigureReason reason = CONFIGURE_REASON_RECONFIGURATION;
+  syncable::ModelTypeSet types_to_download(syncable::BOOKMARKS,
+                                           syncable::PREFERENCES);
+  browser_sync::ModelSafeRoutingInfo new_routing_info;
+  GetModelSafeRoutingInfo(&new_routing_info);
+
+  scoped_ptr<MockSyncScheduler> scheduler(new MockSyncScheduler());
+  ConfigurationParams params;
+  EXPECT_CALL(*scheduler, Start(SyncScheduler::CONFIGURATION_MODE));
+  EXPECT_CALL(*scheduler, ScheduleConfiguration(_)).
+      WillOnce(DoAll(SaveArg<0>(&params), Return(true)));
+  SetScheduler(scheduler.PassAs<SyncScheduler>());
+
+  CallbackCounter ready_task_counter, retry_task_counter;
+  sync_manager_.ConfigureSyncer(
+      reason,
+      types_to_download,
+      new_routing_info,
+      base::Bind(&CallbackCounter::Callback,
+                 base::Unretained(&ready_task_counter)),
+      base::Bind(&CallbackCounter::Callback,
+                 base::Unretained(&retry_task_counter)));
+  EXPECT_EQ(0, ready_task_counter.times_called());
+  EXPECT_EQ(0, retry_task_counter.times_called());
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::RECONFIGURATION,
+            params.source);
+  EXPECT_TRUE(types_to_download.Equals(params.types_to_download));
+  EXPECT_EQ(new_routing_info, params.routing_info);
+}
+
+// Test that the retry callback is invoked on configuration failure.
+TEST_F(SyncManagerTest, ConfigurationRetry) {
+  ConfigureReason reason = CONFIGURE_REASON_RECONFIGURATION;
+  syncable::ModelTypeSet types_to_download(syncable::BOOKMARKS,
+                                           syncable::PREFERENCES);
+  browser_sync::ModelSafeRoutingInfo new_routing_info;
+  GetModelSafeRoutingInfo(&new_routing_info);
+
+  scoped_ptr<MockSyncScheduler> scheduler(new MockSyncScheduler());
+  ConfigurationParams params;
+  EXPECT_CALL(*scheduler, Start(SyncScheduler::CONFIGURATION_MODE));
+  EXPECT_CALL(*scheduler, ScheduleConfiguration(_)).
+      WillOnce(DoAll(SaveArg<0>(&params), Return(false)));
+  SetScheduler(scheduler.PassAs<SyncScheduler>());
+
+  CallbackCounter ready_task_counter, retry_task_counter;
+  sync_manager_.ConfigureSyncer(
+      reason,
+      types_to_download,
+      new_routing_info,
+      base::Bind(&CallbackCounter::Callback,
+                 base::Unretained(&ready_task_counter)),
+      base::Bind(&CallbackCounter::Callback,
+                 base::Unretained(&retry_task_counter)));
+  EXPECT_EQ(0, ready_task_counter.times_called());
+  EXPECT_EQ(1, retry_task_counter.times_called());
+  EXPECT_EQ(sync_pb::GetUpdatesCallerInfo::RECONFIGURATION,
+            params.source);
+  EXPECT_TRUE(types_to_download.Equals(params.types_to_download));
+  EXPECT_EQ(new_routing_info, params.routing_info);
+}
+
 }  // namespace browser_sync
diff --git a/sync/sync.gyp b/sync/sync.gyp
index 73e103c..5372b9d 100644
--- a/sync/sync.gyp
+++ b/sync/sync.gyp
@@ -375,6 +375,7 @@
         'sessions/test_util.h',
         'syncable/syncable_mock.cc',
         'syncable/syncable_mock.h',
+        'test/callback_counter.h',
         'test/engine/fake_model_worker.cc',
         'test/engine/fake_model_worker.h',
         'test/engine/mock_connection_manager.cc',
diff --git a/sync/test/callback_counter.h b/sync/test/callback_counter.h
new file mode 100644
index 0000000..71586ec
--- /dev/null
+++ b/sync/test/callback_counter.h
@@ -0,0 +1,29 @@
+// 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.
+
+#ifndef SYNC_TEST_CALLBACK_COUNTER_H_
+#define SYNC_TEST_CALLBACK_COUNTER_H_
+#pragma once
+
+namespace browser_sync {
+
+// Helper class to track how many times a callback is triggered.
+class CallbackCounter {
+ public:
+  CallbackCounter() { Reset(); }
+  ~CallbackCounter() {}
+
+  void Reset() { times_called_ = 0; }
+  void Callback() { ++times_called_; }
+  int times_called() const { return times_called_; }
+
+ private:
+  int times_called_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackCounter);
+};
+
+}  // namespace browser_sync
+
+#endif  // SYNC_TEST_CALLBACK_COUNTER_H_