Add a flag that lets the webstore show a different UI on app install.

chrome/browser/extensions/extension_webstore_private_apitest.cc

Index: chrome/browser/extensions/extension_webstore_private_apitest.cc
diff --git a/chrome/browser/extensions/extension_webstore_private_apitest.cc b/chrome/browser/extensions/extension_webstore_private_apitest.cc
index 88e772c65119cdae68cc44c5cb97af401b467bbb..68be87212a50d1b7fa2e37df933368dd7d33d119 100644
--- a/chrome/browser/extensions/extension_webstore_private_apitest.cc
+++ b/chrome/browser/extensions/extension_webstore_private_apitest.cc
@@ -106,3 +106,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionWebstorePrivateApiTest,
   ASSERT_TRUE(RunInstallTest("incorrect_manifest2.html", "extension.crx"));
   observer.Wait();
 }
+
+// Tests that we can request an app installed bubble (instead of the default
+// UI when an app is installed).
+IN_PROC_BROWSER_TEST_F(ExtensionWebstorePrivateApiTest,
+                       AppInstallBubble) {
+  ASSERT_TRUE(RunInstallTest("app_install_bubble.html", "app.crx"));
+}