Split ExtensionTestObserver and move to //extensions.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index f2cd2283a0aff63806efe396aed5ccf624e42c9b..8209f833f6013cf4f824952f18876ee494d581fc 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -370,13 +370,13 @@ if (!is_android) {
       "../browser/extensions/browsertest_util.cc",
       "../browser/extensions/clipboard_extension_apitest_chromeos.cc",
       "../browser/extensions/extension_apitest.cc",
+      "../browser/extensions/extension_browser_test_notification_observer.cc",

[Devlin, 2016/10/06 15:52:17]

what about the header?

[Rahul Chaturvedi, 2016/10/11 20:12:35]

Done.

       "../browser/extensions/extension_browsertest.cc",
       "../browser/extensions/extension_commands_global_registry_apitest.cc",
       "../browser/extensions/extension_crash_recovery_browsertest.cc",
       "../browser/extensions/extension_fullscreen_apitest.cc",
       "../browser/extensions/extension_function_test_utils.cc",
       "../browser/extensions/extension_keybinding_apitest.cc",
-      "../browser/extensions/extension_test_notification_observer.cc",
       "../browser/extensions/updater/extension_cache_fake.cc",
       "../browser/extensions/updater/extension_cache_fake.h",
       "../browser/extensions/window_open_interactive_apitest.cc",
@@ -2033,12 +2033,12 @@ test("browser_tests") {
         "../browser/extensions/browsertest_util.h",
         "../browser/extensions/extension_apitest.cc",
         "../browser/extensions/extension_apitest.h",
+        "../browser/extensions/extension_browser_test_notification_observer.cc",
+        "../browser/extensions/extension_browser_test_notification_observer.h",
         "../browser/extensions/extension_browsertest.cc",
         "../browser/extensions/extension_browsertest.h",
         "../browser/extensions/extension_function_test_utils.cc",
         "../browser/extensions/extension_function_test_utils.h",
-        "../browser/extensions/extension_test_notification_observer.cc",
-        "../browser/extensions/extension_test_notification_observer.h",
         "../browser/extensions/updater/extension_cache_fake.cc",
         "../browser/extensions/updater/extension_cache_fake.h",
       ]
@@ -4900,8 +4900,8 @@ if (!is_android && !is_ios && !is_chromecast) {
       "../browser/extensions/api/tab_capture/tab_capture_performancetest.cc",
       "../browser/extensions/browsertest_util.cc",
       "../browser/extensions/extension_apitest.cc",
+      "../browser/extensions/extension_browser_test_notification_observer.cc",
       "../browser/extensions/extension_browsertest.cc",
-      "../browser/extensions/extension_test_notification_observer.cc",
       "../browser/extensions/updater/extension_cache_fake.cc",
       "../browser/extensions/updater/extension_cache_fake.h",
       "base/browser_perf_tests_main.cc",