[Sync] Componentize synced_tab_delegate

components/sync_sessions/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GYP version: components/sync_sessions.gypi:sync_sessions
 source_set("sync_sessions") {
   sources = [
     "revisit/current_tab_matcher.cc",
     "revisit/current_tab_matcher.h",
     "revisit/offset_tab_matcher.cc",
     "revisit/offset_tab_matcher.h",
     "revisit/page_equality.h",
     "revisit/page_visit_observer.h",
     "revisit/sessions_page_revisit_observer.cc",
     "revisit/sessions_page_revisit_observer.h",
     "revisit/typed_url_page_revisit_observer.cc",
     "revisit/typed_url_page_revisit_observer.h",
     "revisit/typed_url_page_revisit_task.cc",
     "revisit/typed_url_page_revisit_task.h",
+    "sync_sessions_client.cc",
+    "sync_sessions_client.h",
+    "synced_tab_delegate.cc",
+    "synced_tab_delegate.h",
   ]
 
   deps = [
     "//base",
     "//components/history/core/browser",
     "//components/sessions",
     "//components/sync_driver",
     "//sync",
   ]
 }
 
+source_set("test_support") {
+  testonly = true
+  sources = [
+    "fake_sync_sessions_client.cc",
+    "fake_sync_sessions_client.h",
+  ]
+
+  public_deps = [
+    ":sync_sessions",
+  ]
+
+  deps = []
+}
+
 source_set("unit_tests") {
   testonly = true
   sources = [
     "revisit/current_tab_matcher_unittest.cc",
     "revisit/offset_tab_matcher_unittest.cc",
     "revisit/sessions_page_revisit_observer_unittest.cc",
     "revisit/typed_url_page_revisit_task_unittest.cc",
   ]
 
   deps = [
     ":sync_sessions",
+    ":test_support",
     "//base/test:test_support",
     "//testing/gtest",
     "//sync",
   ]
 }