chrome://sync-internals string improvements

This updates a few strings on chrome://sync-internals that were
misleading:
"Backend Initialization" becomes "Engine State". "Backend" was renamed
to "Engine" long ago, and the value in the "everything is fine" state is
"Started", which was confusing when applied to "Initialization".
"Syncing" becomes "Sync Cycle Ongoing", because "Syncing: false" was
similarly misleading.

Bug: none
Change-Id: I1e0cddc9b4a74277d67cf69aba83b7695bb8fa07
Reviewed-on: https://chromium-review.googlesource.com/1054671Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558283}

components/sync/driver/about_sync_util.cc

@@ -285,9 +285,9 @@ std::unique_ptr<base::DictionaryValue> ConstructAboutInformation(
   Stat<std::string>* last_synced = section_local->AddStringStat("Last Synced");
   Stat<bool>* is_setup_complete =
       section_local->AddBoolStat("Sync First-Time Setup Complete");
-  Stat<std::string>* backend_initialization =
-      section_local->AddStringStat("Sync Backend Initialization");
-  Stat<bool>* is_syncing = section_local->AddBoolStat("Syncing");
+  Stat<std::string>* engine_initialization_state =
+      section_local->AddStringStat("Sync Engine State");
+  Stat<bool>* is_syncing = section_local->AddBoolStat("Sync Cycle Ongoing");
   Stat<bool>* is_local_sync_enabled =
       section_local->AddBoolStat("Local Sync Backend Enabled");
   Stat<std::string>* local_backend_path =
@@ -417,7 +417,8 @@ std::unique_ptr<base::DictionaryValue> ConstructAboutInformation(
   server_connection->Set(GetConnectionStatus(token_status));
   last_synced->Set(GetLastSyncedTimeString(service->GetLastSyncedTime()));
   is_setup_complete->Set(service->IsFirstSetupComplete());
-  backend_initialization->Set(service->GetEngineInitializationStateString());
+  engine_initialization_state->Set(
+      service->GetEngineInitializationStateString());
   if (is_status_valid)
     is_syncing->Set(full_status.syncing);
   is_local_sync_enabled->Set(service->IsLocalSyncEnabled());

components/sync/engine/sync_status.h

@@ -49,6 +49,7 @@ struct SyncStatus {
   // Number of items successfully committed during most recent sync cycle.
   int committed_count;
 
+  // Whether a sync cycle is going on right now.
   bool syncing;
 
   // Total updates received by the syncer since browser start.