Let AppBannerManager really create and manage banners

chrome/browser/android/banners/app_banner_manager.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ANDROID_BANNERS_APP_BANNER_MANAGER_H_
 #define CHROME_BROWSER_ANDROID_BANNERS_APP_BANNER_MANAGER_H_
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_helper.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/android/meta_tag_observer.h"
+#include "chrome/browser/bitmap_fetcher.h"
 
 namespace content {
 struct FrameNavigateParams;
 struct LoadCommittedDetails;
 }  // namespace content
 
 /**
  * Manages when an app banner is created or dismissed.
  *
  * Hooks the wiring together for getting the data for a particular app.
  * Monitors at most one package at a time, and tracks the info for the
  * most recent app that was requested.  Any work in progress for other apps is
  * discarded.
+ *
+ * The procedure for creating a banner spans multiple asynchronous calls across
+ * the JNI boundary, as well as querying a Service to get info about the app.
+ *
+ * 0) A navigation of the main frame is triggered.  Upon completion of the load,
+ *    the page is parsed for the correct meta tag.  If it doesn't exist, abort.
+ *
+ * 1) The AppBannerManager is alerted about the tag's contents, which should
+ *    be the Play Store package name.  This is sent to the Java side
+ *    AppBannerManager.
+ *
+ * 2) The AppBannerManager's ServiceDelegate is asynchronously queried about the
+ *    package name.
+ *
+ * 3) At some point, the Java-side AppBannerManager is alerted of the completed
+ *    query and is given back data about the requested package, which includes a
+ *    URL for the app's icon.  This URL is sent to native code for retrieval.
+ *
+ * 4) The process of fetching the icon begins by invoking the BitmapFetcher,
+ *    which works asynchonously.
+ *
+ * 5) Once the icon has been downloaded, the icon is sent to the Java-side
+ *    AppBannerManager to (finally) create a AppBannerView, assuming that the
+ *    app we retrieved the details for is still for the page that requested it.
+ *
+ * Because of the asynchronous nature of this pipeline, it's entirely possible
+ * that a request to show a banner is interrupted by another request.  The
+ * Java side manages what happens in these situations, which will usually result
+ * in dropping the old banner request on the floor.
  */
-class AppBannerManager : public MetaTagObserver {
+class AppBannerManager : public chrome::BitmapFetcherDelegate,
+                         public MetaTagObserver {
  public:
   AppBannerManager(JNIEnv* env, jobject obj);
   virtual ~AppBannerManager();
 
   // Destroys the AppBannerManager.
   void Destroy(JNIEnv* env, jobject obj);
 
+  // Blocks a banner for |package_name| from appearing on the domain for |url|.
+  void BlockBanner(JNIEnv* env, jobject obj, jstring jurl, jstring jpackage);
+
   // Observes a new WebContents, if necessary.
   void ReplaceWebContents(JNIEnv* env,
                           jobject obj,
                           jobject jweb_contents);
 
+  // Fetches the icon at the give URL.
+  // Returns |false| if this couldn't be kicked off.
+  bool FetchIcon(JNIEnv* env,
+                 jobject obj,
+                 jstring jimage_url);
+
   // WebContentsObserver overrides.
   virtual void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) OVERRIDE;
 
+  // BitmapFetcherDelegate overrides.
+  virtual void OnFetchComplete(const GURL url, const SkBitmap* bitmap) OVERRIDE;
+
  private:
   // Kicks off the process of showing a banner for the package designated by
   // |tag_content| on the page at the |expected_url|.
   virtual void HandleMetaTagContent(const std::string& tag_content,
                                     const GURL& expected_url) OVERRIDE;
 
+  // Fetches the icon for an app.
+  scoped_ptr<chrome::BitmapFetcher> fetcher_;
+
+  // AppBannerManager on the Java side.
   JavaObjectWeakGlobalRef weak_java_banner_view_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(AppBannerManager);
 };  // class AppBannerManager
 
 // Register native methods
 bool RegisterAppBannerManager(JNIEnv* env);
 
 #endif  // CHROME_BROWSER_ANDROID_BANNERS_APP_BANNER_MANAGER_H_