Implement app banner info bars on desktop.

chrome/browser/banners/app_banner_manager.h

Index: chrome/browser/banners/app_banner_manager.h
diff --git a/chrome/browser/banners/app_banner_manager.h b/chrome/browser/banners/app_banner_manager.h
index a84be6053512a13a9e486103c99699e249c6a007..e2eeab43f549e2e39d2c64d707b94c9956a7fe7f 100644
--- a/chrome/browser/banners/app_banner_manager.h
+++ b/chrome/browser/banners/app_banner_manager.h
@@ -44,12 +44,14 @@ class AppBannerManager : public content::WebContentsObserver,
                      const GURL& validated_url) override;
 
  protected:
+  AppBannerManager(content::WebContents* web_contents, int icon_size);
+
   void ReplaceWebContents(content::WebContents* web_contents);
 
   // Creates an AppBannerDataFetcher, which constructs an app banner.
   virtual AppBannerDataFetcher* CreateAppBannerDataFetcher(
       base::WeakPtr<AppBannerDataFetcher::Delegate> weak_delegate,
-      const int ideal_icon_size);
+      const int ideal_icon_size) = 0;
 
   // Return whether the AppBannerDataFetcher is active.
   bool IsFetcherActive();