[Win] Add a fast profile switcher to the Windows taskbar item.

chrome/browser/ui/startup/startup_browser_creator_browsertest.cc

Index: chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
diff --git a/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc b/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
index b8ef3a7e27dba6c5c668b0c43bd20e6f10074e65..2846164e4dcc6e260dffddfe1fab53e98e6fa1a3 100644
--- a/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
+++ b/chrome/browser/ui/startup/startup_browser_creator_browsertest.cc
@@ -281,6 +281,27 @@ IN_PROC_BROWSER_TEST_F(StartupBrowserCreatorTest,
   ASSERT_EQ(1, new_browser->tab_strip_model()->count());
 }
 
+IN_PROC_BROWSER_TEST_F(StartupBrowserCreatorTest, ActivateExistingBrowser) {
+  // Initially, there should only be one browser open.
+  ASSERT_TRUE(browser());
+  EXPECT_EQ(1u, chrome::GetBrowserCount(browser()->profile(),
+                                        browser()->host_desktop_type()));
+
+  // Add --activate-existing-profile-browser to the command line and
+  // start a new process.
+  CommandLine dummy(CommandLine::NO_PROGRAM);
+  dummy.AppendSwitch(switches::kActivateExistingProfileBrowser);
+
+  StartupBrowserCreator::ProcessCommandLineAlreadyRunning(
+      dummy, base::FilePath(), browser()->profile()->GetPath());
+
+  // This should not have created a new browser window, and should have
+  // activated the existing browser.
+  EXPECT_EQ(1u, chrome::GetBrowserCount(browser()->profile(),
+                                        browser()->host_desktop_type()));
+  EXPECT_TRUE(browser()->window()->IsActive());

[tapted, 2014/11/04 23:10:48]

Calls to IsActive need to be in interactive_ui_tests since another test might
steal focus, but it would be good to avoid moving to an interactive test. I
think repeating the test after closing all windows for the profile would make a
compelling test. (but there's a trap: closing all the windows will hit the
keepalive and start a shutdown procedure, so to avoid that you can probably call
Increment/DecrementKeepAliveCount() in application_lifetime.h. 

Another option would be to create a second profile and open a browser there.
That would be more authentic, but it has to be done asynchronously since the
profile isn't loaded (and it takes a while in debug builds so you might get
flaky timeouts). So, comment to say the increment/decrement calls are being used
to simulate this.

[noms (inactive), 2014/11/10 21:46:08]

I've just removed the check to active, and checking that no new browser got
opened (which is partly correct). This CL is growing up to be a giant, so I
didn't want to block the review on the test. (which I'll work on once I send it
to the owners)

+}
+
 // App shortcuts are not implemented on mac os.
 #if !defined(OS_MACOSX)
 IN_PROC_BROWSER_TEST_F(StartupBrowserCreatorTest, OpenAppShortcutNoPref) {