Move content/child/background_sync to Blink.

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index aa9951d14bd30f5ab86a8ffbac2039ca87ae1ff7..86e22ad565885130419ba1724b03bd6c7af239e0 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -37,7 +37,6 @@
 #include "components/mime_util/mime_util.h"
 #include "content/app/resources/grit/content_resources.h"
 #include "content/app/strings/grit/content_strings.h"
-#include "content/child/background_sync/background_sync_provider.h"
 #include "content/child/child_thread_impl.h"
 #include "content/child/content_child_helpers.h"
 #include "content/child/notifications/notification_dispatcher.h"
@@ -389,8 +388,6 @@ void BlinkPlatformImpl::InternalInit() {
     notification_dispatcher_ =
         ChildThreadImpl::current()->notification_dispatcher();
     push_dispatcher_ = ChildThreadImpl::current()->push_dispatcher();
-    main_thread_sync_provider_.reset(
-        new BackgroundSyncProvider(main_thread_task_runner_.get()));
   }
 }
 
@@ -774,14 +771,6 @@ blink::WebPushProvider* BlinkPlatformImpl::pushProvider() {
                                               push_dispatcher_.get());
 }
 
-blink::WebSyncProvider* BlinkPlatformImpl::backgroundSyncProvider() {
-  if (IsMainThread())
-    return main_thread_sync_provider_.get();
-
-  return BackgroundSyncProvider::GetOrCreateThreadSpecificInstance(
-      main_thread_task_runner_.get());
-}
-
 WebThemeEngine* BlinkPlatformImpl::themeEngine() {
   return &native_theme_engine_;
 }