Implement app banner info bars on desktop.

chrome/browser/banners/app_banner_manager.cc

Index: chrome/browser/banners/app_banner_manager.cc
diff --git a/chrome/browser/banners/app_banner_manager.cc b/chrome/browser/banners/app_banner_manager.cc
index fdbf80b17677caf4fe6eeca51a5d479730fdffaf..f0a81d0cf23271309822073261b5994a92366cc6 100644
--- a/chrome/browser/banners/app_banner_manager.cc
+++ b/chrome/browser/banners/app_banner_manager.cc
@@ -34,6 +34,14 @@ AppBannerManager::AppBannerManager(int icon_size)
       weak_factory_(this) {
 }
 
+AppBannerManager::AppBannerManager(content::WebContents* web_contents,
+                                   int icon_size)
+    : content::WebContentsObserver(web_contents),
+      ideal_icon_size_(icon_size),
+      data_fetcher_(nullptr),
+      weak_factory_(this) {
+}
+
 AppBannerManager::~AppBannerManager() {
   CancelActiveFetcher();
 }
@@ -63,7 +71,6 @@ void AppBannerManager::DidFinishLoad(
   data_fetcher_->Start(validated_url);
 }
 
-
 bool AppBannerManager::HandleNonWebApp(const std::string& platform,
                                        const GURL& url,
                                        const std::string& id) {