Add KVO compliant title property to CWVWebView.

ios/web_view/test/BUILD.gn

 # Copyright 2017 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.
 
 import("//ios/build/config.gni")
 import("//build/config/ios/rules.gni")
 import("//testing/test.gni")
 
 group("all_tests") {
   testonly = true
   deps = [
     ":ios_web_view_inttests",
   ]
 }
 
 test("ios_web_view_inttests") {
   testonly = true
   sources = [
-    "boolean_observer.h",
-    "boolean_observer.mm",
     "chrome_web_view_kvo_inttest.mm",
     "chrome_web_view_test.h",
     "chrome_web_view_test.mm",
     "web_view_interaction_test_util.h",
     "web_view_interaction_test_util.mm",
   ]
 
   deps = [
     "//base",
     "//base/test:run_all_unittests",
     "//ios/testing:ios_test_support",
     "//ios/web_view:web_view+link",
+    "//ios/web_view/test/observers",
     "//net",
     "//net:test_support",
     "//testing/gtest",
   ]
 
   bundle_deps = [ "//ios/web_view:web_view+bundle" ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
 
   assert_no_deps = ios_assert_no_deps
 }