Fix All/HostedAppTest.* browser tests.

This CL modify the window pointer for Web apps, and use the top level
window pointer for Chrome only. For Web apps, still use the tab's
window pointer. This fix is used to fix All/HostedAppTest.* browser
tests, because that tests pull the Web apps to Chrome, which cause the
app id changed in AppService InstanceRegistry, so DCHECK crash:
https://ci.chromium.org/p/chromium/builders/try/linux-chromeos-rel/448712
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8894423355073665120/+/steps/non_viz_browser_tests__with_patch_/0/logs/Deterministic_failure:_All__x2f_HostedAppTest.CtrlClickLink__x2f_0__status_CRASH_/0

BUG=1011235

Change-Id: Id308f394c95196d507d164bb2fe5ac2fbeab406b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1957749
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#724010}

chrome/browser/ui/ash/launcher/app_service_instance_registry_helper.cc

@@ -169,7 +169,10 @@ aura::Window* AppServiceInstanceRegistryHelper::GetWindow(
     content::WebContents* contents) {
   std::string app_id = launcher_controller_helper_->GetAppID(contents);
   aura::Window* window = contents->GetNativeView();
-  if (app_id.empty() || IsWebApp(app_id))
+
+  // If |app_id| is empty, it is a browser tab. Returns the toplevel window in
+  // this case.
+  if (app_id.empty())
     window = window->GetToplevelWindow();
   return window;
 }