Remove --show-app-list-shortcut flag and implement new app launcher enable logic.

chrome/browser/web_applications/web_app.h

Index: chrome/browser/web_applications/web_app.h
diff --git a/chrome/browser/web_applications/web_app.h b/chrome/browser/web_applications/web_app.h
index 4e5f2881bf008b0ef20017a78f6b0b59661c5502..af86986173e31fd1146a096b238fca6758b5fab4 100644
--- a/chrome/browser/web_applications/web_app.h
+++ b/chrome/browser/web_applications/web_app.h
@@ -96,6 +96,9 @@ namespace internals {
 #if defined(OS_WIN)
 bool CheckAndSaveIcon(const base::FilePath& icon_file,
                       const gfx::ImageFamily& image);
+
+std::vector<base::FilePath> GetShortcutPaths(
+    const ShellIntegration::ShortcutLocations& creation_locations);
 #endif
 
 // Implemented for each platform, does the platform specific parts of creating