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..190308da83a3312e6ee781ea86edbb5ca368ef48 100644
--- a/chrome/browser/banners/app_banner_manager.h
+++ b/chrome/browser/banners/app_banner_manager.h
@@ -10,6 +10,7 @@
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/banners/app_banner_data_fetcher.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_user_data.h"
 #include "third_party/WebKit/public/platform/modules/app_banner/WebAppBannerPromptReply.h"
 
 namespace content {
@@ -28,7 +29,8 @@ class AppBannerDataFetcher;
  * requested app. Any work in progress for other apps is discarded.
  */
 class AppBannerManager : public content::WebContentsObserver,
-                         public AppBannerDataFetcher::Delegate {
+                         public AppBannerDataFetcher::Delegate,
+                         public content::WebContentsUserData<AppBannerManager> {
  public:
   static bool IsEnabled();
   static void DisableSecureSchemeCheckForTesting();
@@ -58,6 +60,9 @@ class AppBannerManager : public content::WebContentsObserver,
   int ideal_icon_size() { return ideal_icon_size_; }
 
  private:
+  explicit AppBannerManager(content::WebContents* web_contents);
+  friend class content::WebContentsUserData<AppBannerManager>;
+
   // AppBannerDataFetcher::Delegate overrides.
   bool HandleNonWebApp(const std::string& platform,
                        const GURL& url,