[App banners] Start addressing race conditions

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_weak_ref.h"
 #include "base/memory/ref_counted.h"
@@ skipping 49 matching lines @@
  *    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.
  */
 
 namespace banners {
 
-class AppBannerManager : public chrome::BitmapFetcherDelegate,
-                         public content::WebContentsObserver {
+class AppBannerManager : public content::WebContentsObserver {
  public:
+  class BannerBitmapFetcher;
+
   AppBannerManager(JNIEnv* env, jobject obj);
   ~AppBannerManager() override;
 
   // Destroys the AppBannerManager.
   void Destroy(JNIEnv* env, jobject obj);
 
   // Observes a new WebContents, if necessary.
   void ReplaceWebContents(JNIEnv* env,
                           jobject obj,
                           jobject jweb_contents);
 
   // Called when the Java-side has retrieved information for the app.
   // Returns |false| if an icon fetch couldn't be kicked off.
   bool OnAppDetailsRetrieved(JNIEnv* env,
                              jobject obj,
                              jobject japp_data,
                              jstring japp_title,
                              jstring japp_package,
                              jstring jicon_url);
 
   // Fetches the icon at the given URL asynchronously.
   // Returns |false| if this couldn't be kicked off.
   bool FetchIcon(const GURL& image_url);
 
-  // Return how many fetchers are active.
-  int GetNumActiveFetchers(JNIEnv* env, jobject jobj);
+  // Called when everything required to show a banner is ready.
+  void OnFetchComplete(BannerBitmapFetcher* fetcher,
+                       const GURL url,
+                       const SkBitmap* icon);
+
+  // Return whether a BitmapFetcher is active.
+  bool IsFetcherActive(JNIEnv* env, jobject jobj);
 
   // Returns the current time.
   static base::Time GetCurrentTime();
 
   // WebContentsObserver overrides.
   void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) override;
   void DidFinishLoad(content::RenderFrameHost* render_frame_host,
                      const GURL& validated_url) override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
-  // BitmapFetcherDelegate overrides.
-  void OnFetchComplete(const GURL url, const SkBitmap* bitmap) override;
-
  private:
   // Gets the preferred icon size for the banner icons.
   int GetPreferredIconSize();
 
   // Called when the manifest has been retrieved, or if there is no manifest to
   // retrieve.
   void OnDidGetManifest(const content::Manifest& manifest);
 
   // Called when the renderer has returned information about the meta tag.
   // If there is some metadata for the play store tag, this kicks off the
   // process of showing a banner for the package designated by |tag_content| on
   // the page at the |expected_url|.
   void OnDidRetrieveMetaTagContent(bool success,
                                    const std::string& tag_name,
                                    const std::string& tag_content,
                                    const GURL& expected_url);
 
   // Called when the result of the CheckHasServiceWorker query has completed.
   void OnDidCheckHasServiceWorker(bool has_service_worker);
 
   // Record that the banner could be shown at this point, if the triggering
   // heuristic allowed.
   void RecordCouldShowBanner(const std::string& package_or_start_url);
 
   // Check if the banner should be shown.
   bool CheckIfShouldShow(const std::string& package_or_start_url);
 
-  // Fetches the icon for an app.
-  scoped_ptr<chrome::BitmapFetcher> fetcher_;
+  // Cancels an active BitmapFetcher, stopping its banner from appearing.
+  void CancelActiveFetcher();
+
+  // Fetches the icon for an app.  Weakly held because they delete themselves.
+  BannerBitmapFetcher* fetcher_;
+
   GURL validated_url_;
   GURL app_icon_url_;
 
   base::string16 app_title_;
 
   content::Manifest web_app_data_;
 
   base::android::ScopedJavaGlobalRef<jobject> native_app_data_;
   std::string native_app_package_;
 
   // AppBannerManager on the Java side.
   JavaObjectWeakGlobalRef weak_java_banner_view_manager_;
 
   // A weak pointer is used as the lifetime of the ServiceWorkerContext is
   // longer than the lifetime of this banner manager. The banner manager
   // might be gone when calls sent to the ServiceWorkerContext are completed.
   base::WeakPtrFactory<AppBannerManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AppBannerManager);
 };  // class AppBannerManager
 
 // Register native methods
 bool RegisterAppBannerManager(JNIEnv* env);
 
 }  // namespace banners
 
 #endif  // CHROME_BROWSER_ANDROID_BANNERS_APP_BANNER_MANAGER_H_