[Offline pages] Detecting missing offline copy

chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java

Index: chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java
index f488ab0028deb814ab9929ce31dbec670c6dd88e..030b8d95fa41fa1a12cd2ce90feb43d3efb76d21 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarksModel.java
@@ -93,6 +93,9 @@ public class EnhancedBookmarksModel extends BookmarksBridge {
                             notifyBookmarkModelLoaded();
                         }
                     }
+
+                    @Override
+                    public void offlinePageDeleted(BookmarkId bookmarkId) {}
                 };
                 mOfflinePageBridge.addObserver(mOfflinePageModelObserver);
             }
@@ -105,6 +108,7 @@ public class EnhancedBookmarksModel extends BookmarksBridge {
     @Override
     public void destroy() {
         if (mOfflinePageBridge != null) {
+            mOfflinePageBridge.removeObserver(mOfflinePageModelObserver);
             mOfflinePageBridge.destroy();
             mOfflinePageBridge = null;
         }