Move offline related functions from Tab to OfflinePageUtils

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

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageTabObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageTabObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageTabObserver.java
index 04015df1c9d131fca5e9126e5eb729749f69ad88..c1dff32614a6b70f35510d6b0f4944520332140a 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageTabObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageTabObserver.java
@@ -171,7 +171,7 @@ public class OfflinePageTabObserver
     @Override
     public void onUrlUpdated(Tab tab) {
         Log.d(TAG, "onUrlUpdated");
-        if (!tab.isOfflinePage()) {
+        if (!isOfflinePage(tab)) {
             stopObservingTab(tab);
         } else {
             if (isObservingTab(tab)) {
@@ -184,7 +184,7 @@ public class OfflinePageTabObserver
     }
 
     void startObservingTab(Tab tab) {
-        if (!tab.isOfflinePage()) return;
+        if (!isOfflinePage(tab)) return;
 
         mCurrentTab = tab;
 
@@ -285,9 +285,14 @@ public class OfflinePageTabObserver
         return OfflinePageUtils.isShowingOfflinePreview(tab);
     }
 
+    @VisibleForTesting
+    boolean isOfflinePage(Tab tab) {
+        return OfflinePageUtils.isOfflinePage(tab);
+    }
+
     void maybeShowReloadSnackbar(Tab tab, boolean isNetworkEvent) {
         // Exclude Offline Previews, as there is a seperate UI for previews.
-        if (tab == null || tab.isFrozen() || tab.isHidden() || !tab.isOfflinePage()
+        if (tab == null || tab.isFrozen() || tab.isHidden() || !isOfflinePage(tab)
                 || isShowingOfflinePreview(tab) || !isConnected() || !isLoadedTab(tab)
                 || (wasSnackbarSeen(tab) && !isNetworkEvent)) {
             // Conditions to show a snackbar are not met.