Reland 89038, but with a mocked out keychain (mac unit tests were timing out)

chrome/browser/sync/glue/sync_backend_host.cc

Index: chrome/browser/sync/glue/sync_backend_host.cc
diff --git a/chrome/browser/sync/glue/sync_backend_host.cc b/chrome/browser/sync/glue/sync_backend_host.cc
index 93169618c5140fa2d3a74254c2398337e1325762..f83755f4d1aacccf5da89efe3105165b56cbd27a 100644
--- a/chrome/browser/sync/glue/sync_backend_host.cc
+++ b/chrome/browser/sync/glue/sync_backend_host.cc
@@ -979,6 +979,9 @@ void SyncBackendHost::HandleInitializationCompletedOnFrontendLoop() {
   if (!frontend_)
     return;
   syncapi_initialized_ = true;
+  // Now that the syncapi is initialized, we can update the cryptographer (and
+  // can handle any ON_PASSPHRASE_REQUIRED notifications that may arise).
+  core_->syncapi()->RefreshEncryption();
   frontend_->OnBackendInitialized();
 }