Hook up CryptAuthGCMManager to the enrollment and device sync managers.

components/proximity_auth/cryptauth/cryptauth_device_manager.cc

Index: components/proximity_auth/cryptauth/cryptauth_device_manager.cc
diff --git a/components/proximity_auth/cryptauth/cryptauth_device_manager.cc b/components/proximity_auth/cryptauth/cryptauth_device_manager.cc
index 396d1915fd1939c457a30c029e9c3520e12d230d..3e641bbc96c31a01d3ff92cbea28cb59553ea1fc 100644
--- a/components/proximity_auth/cryptauth/cryptauth_device_manager.cc
+++ b/components/proximity_auth/cryptauth/cryptauth_device_manager.cc
@@ -88,14 +88,16 @@ bool DictionaryToUnlockKey(const base::DictionaryValue& dictionary,
 CryptAuthDeviceManager::CryptAuthDeviceManager(
     scoped_ptr<base::Clock> clock,
     scoped_ptr<CryptAuthClientFactory> client_factory,
+    CryptAuthGCMManager* gcm_manager,
     PrefService* pref_service)
     : clock_(clock.Pass()),
       client_factory_(client_factory.Pass()),
+      gcm_manager_(gcm_manager),
       pref_service_(pref_service),
-      weak_ptr_factory_(this) {
-}
+      weak_ptr_factory_(this) {}
 
 CryptAuthDeviceManager::~CryptAuthDeviceManager() {
+  gcm_manager_->RemoveObserver(this);
 }
 
 // static
@@ -112,6 +114,8 @@ void CryptAuthDeviceManager::RegisterPrefs(PrefRegistrySimple* registry) {
 void CryptAuthDeviceManager::Start() {
   UpdateUnlockKeysFromPrefs();
 
+  gcm_manager_->AddObserver(this);
+
   base::Time last_successful_sync = GetLastSyncTime();
   base::TimeDelta elapsed_time_since_last_sync =
       clock_->Now() - last_successful_sync;
@@ -216,6 +220,10 @@ scoped_ptr<SyncScheduler> CryptAuthDeviceManager::CreateSyncScheduler() {
       kDeviceSyncMaxJitterRatio, "CryptAuth DeviceSync"));
 }
 
+void CryptAuthDeviceManager::OnResyncMessage() {
+  ForceSyncNow(cryptauth::INVOCATION_REASON_SERVER_INITIATED);
+}
+
 void CryptAuthDeviceManager::UpdateUnlockKeysFromPrefs() {
   const base::ListValue* unlock_key_list =
       pref_service_->GetList(prefs::kCryptAuthDeviceSyncUnlockKeys);