[Offline pages] Update of OfflinePageUtils for better testability

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java
index fb0f227cdc53ddd4ab7b6a36e878228fa5bd0d71..54e0c0e2799083b71c68fb03f8eac88297abb101 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java
@@ -76,7 +76,8 @@ public class OfflinePageUtils {
     // Used instead of the constant so tests can override the value.
     private static int sSnackbarDurationMs = DEFAULT_SNACKBAR_DURATION_MS;
 
-    private static OfflinePageUtils sInstance;
+    /** Instance carrying actual implementation of utility methods. */
+    private static Internal sInstance;
 
     private static File sOfflineSharingDirectory;
 
@@ -88,6 +89,88 @@ public class OfflinePageUtils {
     private static Map<ChromeActivity, RecentTabTracker> sTabModelObservers = new HashMap<>();
 
     /**
+     * Interface for implementation of offline page utilities, that can be implemented for testing.
+     * We are using an internal interface, so that instance methods can have the same names as
+     * static methods.
+     */
+    @VisibleForTesting
+    interface Internal {
+        /** Returns offline page bridge for specified profile. */
+        OfflinePageBridge getOfflinePageBridge(Profile profile);
+
+        /** Returns whether the network is connected. */
+        boolean isConnected();
+
+        /**
+         * Checks if an offline page is shown for the tab.
+         * @param tab The tab to be reloaded.
+         * @return True if the offline page is opened.
+         */
+        boolean isOfflinePage(Tab tab);
+
+        /**
+         * Returns whether the tab is showing offline preview.
+         * @param tab The current tab.
+         */
+        boolean isShowingOfflinePreview(Tab tab);
+
+        /**
+         * Shows the "reload" snackbar for the given tab.
+         * @param context The application context.
+         * @param snackbarManager Class that shows the snackbar.
+         * @param snackbarController Class to control the snackbar.
+         * @param tabId Id of a tab that the snackbar is related to.
+         */
+        void showReloadSnackbar(Context context, SnackbarManager snackbarManager,
+                final SnackbarController snackbarController, int tabId);
+    }
+
+    private static class OfflinePageUtilsImpl implements Internal {
+        @Override
+        public OfflinePageBridge getOfflinePageBridge(Profile profile) {
+            return OfflinePageBridge.getForProfile(profile);
+        }
+
+        @Override
+        public boolean isConnected() {
+            return NetworkChangeNotifier.isOnline();
+        }
+
+        @Override
+        public boolean isOfflinePage(Tab tab) {
+            WebContents webContents = tab.getWebContents();
+            if (webContents == null) return false;
+            OfflinePageBridge offlinePageBridge =
+                    getInstance().getOfflinePageBridge(tab.getProfile());
+            if (offlinePageBridge == null) return false;
+            return offlinePageBridge.isOfflinePage(webContents);
+        }
+
+        @Override
+        public boolean isShowingOfflinePreview(Tab tab) {
+            OfflinePageBridge offlinePageBridge = getOfflinePageBridge(tab.getProfile());
+            if (offlinePageBridge == null) return false;
+            return offlinePageBridge.isShowingOfflinePreview(tab.getWebContents());
+        }
+
+        @Override
+        public void showReloadSnackbar(Context context, SnackbarManager snackbarManager,
+                final SnackbarController snackbarController, int tabId) {
+            if (tabId == Tab.INVALID_TAB_ID) return;
+
+            Log.d(TAG, "showReloadSnackbar called with controller " + snackbarController);
+            Snackbar snackbar =
+                    Snackbar.make(context.getString(R.string.offline_pages_viewing_offline_page),
+                                    snackbarController, Snackbar.TYPE_ACTION,
+                                    Snackbar.UMA_OFFLINE_PAGE_RELOAD)
+                            .setSingleLine(false)
+                            .setAction(context.getString(R.string.reload), tabId);
+            snackbar.setDuration(sSnackbarDurationMs);
+            snackbarManager.showSnackbar(snackbar);
+        }
+    }
+
+    /**
      * Contains values from the histogram enum OfflinePagesTabRestoreType used for reporting the
      * OfflinePages.TabRestore metric.
      */
@@ -107,9 +190,9 @@ public class OfflinePageUtils {
         public static final int COUNT = 10;
     }
 
-    private static OfflinePageUtils getInstance() {
+    private static Internal getInstance() {
         if (sInstance == null) {
-            sInstance = new OfflinePageUtils();
+            sInstance = new OfflinePageUtilsImpl();
         }
         return sInstance;
     }
@@ -128,11 +211,9 @@ public class OfflinePageUtils {
         return Environment.getDataDirectory().getTotalSpace();
     }
 
-    /**
-     * Returns true if the network is connected.
-     */
+    /** Returns whether the network is connected. */
     public static boolean isConnected() {
-        return NetworkChangeNotifier.isOnline();
+        return getInstance().isConnected();
     }
 
     /*
@@ -203,25 +284,21 @@ public class OfflinePageUtils {
         OfflinePageTabObserver.addObserverForTab(tab);
     }
 
+    protected void showReloadSnackbarInternal(Context context, SnackbarManager snackbarManager,
+            final SnackbarController snackbarController, int tabId) {}
+
     /**
      * Shows the "reload" snackbar for the given tab.
-     * @param activity The activity owning the tab.
-     * @param snackbarController Class to show the snackbar.
+     * @param context The application context.
+     * @param snackbarManager Class that shows the snackbar.
+     * @param snackbarController Class to control the snackbar.
+     * @param tabId Id of a tab that the snackbar is related to.
      */
     public static void showReloadSnackbar(Context context, SnackbarManager snackbarManager,
             final SnackbarController snackbarController, int tabId) {
-        if (tabId == Tab.INVALID_TAB_ID) return;
-
-        Log.d(TAG, "showReloadSnackbar called with controller " + snackbarController);
-        Snackbar snackbar =
-                Snackbar.make(context.getString(R.string.offline_pages_viewing_offline_page),
-                        snackbarController, Snackbar.TYPE_ACTION, Snackbar.UMA_OFFLINE_PAGE_RELOAD)
-                        .setSingleLine(false).setAction(context.getString(R.string.reload), tabId);
-        snackbar.setDuration(sSnackbarDurationMs);
-        snackbarManager.showSnackbar(snackbar);
+        getInstance().showReloadSnackbar(context, snackbarManager, snackbarController, tabId);
     }
 
-
     /**
      * Records UMA data when the Offline Pages Background Load service awakens.
      * @param context android context
@@ -558,9 +635,7 @@ public class OfflinePageUtils {
      * @param tab The current tab.
      */
     public static boolean isShowingOfflinePreview(Tab tab) {
-        OfflinePageBridge offlinePageBridge = getInstance().getOfflinePageBridge(tab.getProfile());
-        if (offlinePageBridge == null) return false;
-        return offlinePageBridge.isShowingOfflinePreview(tab.getWebContents());
+        return getInstance().isShowingOfflinePreview(tab);
     }
 
     /**
@@ -569,11 +644,7 @@ public class OfflinePageUtils {
      * @return True if the offline page is opened.
      */
     public static boolean isOfflinePage(Tab tab) {
-        WebContents webContents = tab.getWebContents();
-        if (webContents == null) return false;
-        OfflinePageBridge offlinePageBridge = getInstance().getOfflinePageBridge(tab.getProfile());
-        if (offlinePageBridge == null) return false;
-        return offlinePageBridge.isOfflinePage(webContents);
+        return getInstance().isOfflinePage(tab);
     }
 
     /**
@@ -617,10 +688,6 @@ public class OfflinePageUtils {
         tab.loadUrl(params);
     }
 
-    protected OfflinePageBridge getOfflinePageBridge(Profile profile) {
-        return OfflinePageBridge.getForProfile(profile);
-    }
-
     /**
      * Tracks tab creation and closure for the Recent Tabs feature.  UI needs to stop showing
      * recent offline pages as soon as the tab is closed.  The TabModel is used to get profile
@@ -792,7 +859,7 @@ public class OfflinePageUtils {
     }
 
     @VisibleForTesting
-    static void setInstanceForTesting(OfflinePageUtils instance) {
+    static void setInstanceForTesting(Internal instance) {
         sInstance = instance;
     }