Prefer SyncService over ProfileSyncService in foreign_session_helper

SyncService is the interface, ProfileSyncService is the concrete
implementation. Generally no clients should need to use the conrete
implementation - for one, testing will be much easier once everyone
uses the interface only.

Bug: 924508
Change-Id: Ia210665f8f02512053d1a60d627dea0f22758387
Reviewed-on: https://chromium-review.googlesource.com/c/1461119
Auto-Submit: Marc Treib <treib@chromium.org>
Commit-Queue: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630662}
void ForeignSessionHelper::DeleteForeignSession(
    JNIEnv* env,
    const JavaParamRef<jobject>& obj,
    const JavaParamRef<jstring>& session_tag) {
  OpenTabsUIDelegate* open_tabs = GetOpenTabsUIDelegate(profile_);
  if (open_tabs)
    open_tabs->DeleteForeignSession(ConvertJavaStringToUTF8(env, session_tag));
}

void ForeignSessionHelper::DeleteForeignSession(
    JNIEnv* env,
    const JavaParamRef<jobject>& obj,
    const JavaParamRef<jstring>& session_tag) {
  OpenTabsUIDelegate* open_tabs = GetOpenTabsUIDelegate(profile_);
  if (open_tabs)
    open_tabs->DeleteForeignSession(ConvertJavaStringToUTF8(env, session_tag));
}
