Refactor the Java AppBannerManager to be owned by native code.

chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java b/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
index 19f4531ee843bf071aeeb98c7d70f283938dc009..b3e0dea497d509976be38c1d550bda98792b6fab 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
@@ -12,44 +12,50 @@ import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.chrome.browser.ShortcutHelper;
-import org.chromium.chrome.browser.tab.EmptyTabObserver;
-import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.content_public.browser.WebContents;
 
 /**
  * Manages an AppBannerInfoBar for a Tab.
  *
- * The AppBannerManager manages a single AppBannerInfoBar, creating a new one when it detects that
- * the current webpage is requesting a banner to be built. The actual observation of the WebContents
- * (which triggers the automatic creation and removal of banners, among other things) is done by the
- * native-side AppBannerManager.
- *
- * This Java-side class owns its native-side counterpart, which is basically used to grab resources
- * from the network.
+ * The AppBannerManager is responsible for fetching details about native apps to display in the
+ * banner. The actual observation of the WebContents (which triggers the automatic creation and
+ * removal of banners, among other things) is done by the native-side AppBannerManagerAndroid.
  */
 @JNINamespace("banners")
-public class AppBannerManager extends EmptyTabObserver {
+public class AppBannerManager {
     private static final String TAG = "AppBannerManager";
 
     /** Retrieves information about a given package. */
     private static AppDetailsDelegate sAppDetailsDelegate;
 
-    /** Whether the banners are enabled. */
-    private static Boolean sIsEnabled;
+    /** Whether add to home screen is permitted by the system. */
+    private static Boolean sIsSupported;
+
+    /** Whether the tab to which this manager is attached to is permitted to show banners. */
+    private boolean mIsEnabledForTab;
 
     /** Pointer to the native side AppBannerManager. */
     private long mNativePointer;
 
     /**
-     * Checks if app banners are enabled.
-     * @return True if banners are enabled, false otherwise.
+     * Checks if the add to home screen intent is supported.
+     * @return true if add to home screen is supported, false otherwise.
      */
-    public static boolean isEnabled() {
-        if (sIsEnabled == null) {
+    public static boolean isSupported() {
+        if (sIsSupported == null) {
             Context context = ContextUtils.getApplicationContext();
-            sIsEnabled = ShortcutHelper.isAddToHomeIntentSupported(context);
+            sIsSupported = ShortcutHelper.isAddToHomeIntentSupported(context);
         }
-        return sIsEnabled;
+        return sIsSupported;
+    }
+
+    /**
+     * Checks if app banners are enabled for the tab which this manager is attached to.
+     * @return true if app banners can be shown for this tab, false otherwise.
+     */
+    @CalledByNative
+    private boolean isEnabledForTab() {
+        return isSupported() && mIsEnabledForTab;
     }
 
     /**
@@ -62,41 +68,25 @@ public class AppBannerManager extends EmptyTabObserver {
     }
 
     /**
-     * Constructs an AppBannerManager for the given tab.
-     * @param tab Tab that the AppBannerManager will be attached to.
+     * Constructs an AppBannerManager.
+     * @param nativePointer the native-side object that owns this AppBannerManager.
      */
-    public AppBannerManager(Tab tab, Context context) {
-        mNativePointer = nativeInit();
-        updatePointers(tab);
+    private AppBannerManager(long nativePointer) {
+        mNativePointer = nativePointer;
+        mIsEnabledForTab = isSupported();
     }
 
-    @Override
-    public void onWebContentsSwapped(Tab tab, boolean didStartLoad,
-            boolean didFinishLoad) {
-        updatePointers(tab);
-    }
-
-    @Override
-    public void onContentChanged(Tab tab) {
-        updatePointers(tab);
+    @CalledByNative
+    private static AppBannerManager create(long nativePointer) {
+        return new AppBannerManager(nativePointer);
     }
 
-    /**
-     * Destroys the native AppBannerManager.
-     */
-    public void destroy() {
-        nativeDestroy(mNativePointer);
+    @CalledByNative
+    private void destroy() {
         mNativePointer = 0;
     }
 
     /**
-     * Updates which WebContents the native AppBannerManager is monitoring.
-     */
-    private void updatePointers(Tab tab) {
-        nativeReplaceWebContents(mNativePointer, tab.getWebContents());
-    }
-
-    /**
      * Grabs package information for the banner asynchronously.
      * @param url         URL for the page that is triggering the banner.
      * @param packageName Name of the package that is being advertised.
@@ -133,15 +123,15 @@ public class AppBannerManager extends EmptyTabObserver {
         };
     }
 
-    /** Requests the app banner. This method is called from the DevTools. */
-    public void requestAppBanner() {
-        nativeRequestAppBanner(mNativePointer);
+    /** Enables or disables app banners. */
+    public void setIsEnabledForTab(boolean state) {
+        mIsEnabledForTab = state;
     }
 
-    /** Enables or disables the app banners for testing. */
+    /** Overrides whether the system supports add to home screen. Used in testing. */
     @VisibleForTesting
-    static void setIsEnabledForTesting(boolean state) {
-        sIsEnabled = state;
+    public static void setIsSupported(boolean state) {
+        sIsSupported = state;
     }
 
     /** Sets a constant (in days) that gets added to the time when the current time is requested. */
@@ -162,19 +152,21 @@ public class AppBannerManager extends EmptyTabObserver {
         nativeSetEngagementWeights(directEngagement, indirectEngagement);
     }
 
-    /** Returns whether a AppBannerDataFetcher is actively retrieving data. */
+    /** Returns whether an AppBannerDataFetcher is actively retrieving data. */
     @VisibleForTesting
     public boolean isFetcherActiveForTesting() {
         return nativeIsFetcherActive(mNativePointer);
     }
 
-    private native long nativeInit();
-    private native void nativeDestroy(long nativeAppBannerManagerAndroid);
-    private native void nativeReplaceWebContents(long nativeAppBannerManagerAndroid,
+    /** Returns the AppBannerManager object. This is owned by the C++ banner manager. */
+    public static AppBannerManager getAppBannerManagerForWebContents(WebContents webContents) {
+        return nativeGetJavaBannerManagerForWebContents(webContents);
+    }
+
+    private static native AppBannerManager nativeGetJavaBannerManagerForWebContents(
             WebContents webContents);
     private native boolean nativeOnAppDetailsRetrieved(long nativeAppBannerManagerAndroid,
             AppData data, String title, String packageName, String imageUrl);
-    private native void nativeRequestAppBanner(long nativeAppBannerManagerAndroid);
 
     // Testing methods.
     private static native void nativeSetTimeDeltaForTesting(int days);