Add support for deferring app initialization when testing.

chrome/test/remoting/remote_desktop_browsertest.cc

Index: chrome/test/remoting/remote_desktop_browsertest.cc
diff --git a/chrome/test/remoting/remote_desktop_browsertest.cc b/chrome/test/remoting/remote_desktop_browsertest.cc
index 80160d5312f52ce1cb223806d121ff9b81e99a34..b7fa8d0d87287dc8fd83d646b285063960442382 100644
--- a/chrome/test/remoting/remote_desktop_browsertest.cc
+++ b/chrome/test/remoting/remote_desktop_browsertest.cc
@@ -166,7 +166,7 @@ void RemoteDesktopBrowserTest::VerifyChromotingLoaded(bool expected) {
   ASSERT_EQ(installed, expected);
 }
 
-void RemoteDesktopBrowserTest::LaunchChromotingApp() {
+void RemoteDesktopBrowserTest::LaunchChromotingApp(bool defer_start) {
   ASSERT_TRUE(extension_);
 
   GURL chromoting_main = Chromoting_Main_URL();
@@ -174,13 +174,26 @@ void RemoteDesktopBrowserTest::LaunchChromotingApp() {
   // loaded could be the generated background page. We need to wait
   // till the chromoting main page is loaded.
   PageLoadNotificationObserver observer(chromoting_main);
+  observer.set_ignore_url_parameters(true);
+
+  extensions::FeatureSwitch::ScopedOverride enable_trace_app_source(
+      extensions::FeatureSwitch::trace_app_source(),
+      true);
+
+  // Lacking any other convenient mechanism for passing a URL parameter to the
+  // web-app, we use the |source| field. Since there's no way to launch the
+  // app from the About page, this should never be encountered by real users,
+  // even if they have the trace_app_source command-line option enabled.

[Jamie, 2014/12/02 01:30:13]

cylee@: What I would like to do here is add a BROWSER_TEST member to the
AppLaunchSource enum, but the comment about its inclusion in UMA stats makes me
suspect that I don't fully understand the ramifications of doing so. Would you
be supportive of a separate CL to add that so that I can use it in this one? If
not, then I think this is safe, but it's a bit of a hack.

[cylee1, 2014/12/02 14:10:32]

Adding a new enum BROWSER_TEST sounds much reasonable than using
SOURCE_ABOUT_PAGE to me.
It would be recorded in ChromeOS UMA system but I guess it's fine.

Note that you'll need to modify 
extensions/common/api/app_runtime.idl
tools/metrics/histograms/histograms.xml
extensions/common/constants.h
and 
extensions/browser/api/app_runtime/app_runtime_api.cc
for the enum mapping.

+  extensions::AppLaunchSource source =
+      defer_start ? extensions::SOURCE_ABOUT_PAGE
+                  : extensions::SOURCE_UNTRACKED;
 
   OpenApplication(AppLaunchParams(browser()->profile(), extension_,
                                   is_platform_app()
                                       ? extensions::LAUNCH_CONTAINER_NONE
                                       : extensions::LAUNCH_CONTAINER_TAB,
                                   is_platform_app() ? NEW_WINDOW : CURRENT_TAB,
-                                  extensions::SOURCE_UNTRACKED));
+                                  source));
 
   observer.Wait();
 
@@ -210,6 +223,10 @@ void RemoteDesktopBrowserTest::LaunchChromotingApp() {
   EXPECT_EQ(Chromoting_Main_URL(), GetCurrentURL());
 }
 
+void RemoteDesktopBrowserTest::StartChromotingApp() {
+  ClickOnControl("browser-test-continue-init");
+};
+
 void RemoteDesktopBrowserTest::Authorize() {
   // The chromoting extension should be installed.
   ASSERT_TRUE(extension_);
@@ -465,7 +482,7 @@ void RemoteDesktopBrowserTest::Cleanup() {
 void RemoteDesktopBrowserTest::SetUpTestForMe2Me() {
   VerifyInternetAccess();
   Install();
-  LaunchChromotingApp();
+  LaunchChromotingApp(false);
   Auth();
   LoadScript(app_web_content(), FILE_PATH_LITERAL("browser_test.js"));
   ExpandMe2Me();