[Sync] Add support for performing a GetKey on startup.

sync/test/engine/mock_connection_manager.h

Index: sync/test/engine/mock_connection_manager.h
diff --git a/sync/test/engine/mock_connection_manager.h b/sync/test/engine/mock_connection_manager.h
index f58cf2273cfa31f239bde201342171a8f5c1cd6b..0951fe0ef8a82086cdff9c9e3297c878d27ddf42 100644
--- a/sync/test/engine/mock_connection_manager.h
+++ b/sync/test/engine/mock_connection_manager.h
@@ -122,6 +122,9 @@ class MockConnectionManager : public syncer::ServerConnectionManager {
   void FailNextPostBufferToPathCall() { countdown_to_postbuffer_fail_ = 1; }
   void FailNthPostBufferToPathCall(int n) { countdown_to_postbuffer_fail_ = n; }
 
+  void SetKeystoreKey(const std::string& key);
+  void SetGetKeyResponseStatus(sync_pb::SyncEnums::ErrorType errortype);
+
   void FailNonPeriodicGetUpdates() { fail_non_periodic_get_updates_ = true; }
 
   // Simple inspectors.
@@ -236,6 +239,8 @@ class MockConnectionManager : public syncer::ServerConnectionManager {
                      sync_pb::ClientToServerResponse* response_buffer);
   void ProcessClearData(sync_pb::ClientToServerMessage* csm,
                         sync_pb::ClientToServerResponse* response);
+  void ProcessGetKey(sync_pb::ClientToServerMessage* csm,
+                     sync_pb::ClientToServerResponse* response);
   void AddDefaultBookmarkData(sync_pb::SyncEntity* entity, bool is_folder);
 
   // Determine if one entry in a commit should be rejected with a conflict.
@@ -307,6 +312,11 @@ class MockConnectionManager : public syncer::ServerConnectionManager {
   // The clear data response we'll return in the next response
   sync_pb::SyncEnums::ErrorType clear_user_data_response_errortype_;
 
+  // The keystore key we return in a GetKey response.
+  std::string keystore_key_;
+  // The GetKey response we'll next return.
+  sync_pb::SyncEnums::ErrorType get_key_response_errortype_;
+
   // The AUTHENTICATE response we'll return for auth requests.
   sync_pb::AuthenticateResponse auth_response_;
   // What we use to determine if we should return SUCCESS or BAD_AUTH_TOKEN.