[Offline pages] Detecting missing offline copy

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

Index: chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkEditActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkEditActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkEditActivity.java
index d20ec1b303589c62c0dca259fe7336ca079dd9c1..48b0ad5144e0b93fc683f432207230832675af4f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkEditActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkEditActivity.java
@@ -23,6 +23,7 @@ import org.chromium.chrome.browser.BookmarksBridge.BookmarkModelObserver;
 import org.chromium.chrome.browser.UrlUtilities;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge.DeletePageCallback;
+import org.chromium.chrome.browser.offlinepages.OfflinePageBridge.OfflinePageModelObserver;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge.SavePageCallback;
 import org.chromium.chrome.browser.offlinepages.OfflinePageItem;
 import org.chromium.chrome.browser.widget.EmptyAlertEditText;
@@ -60,6 +61,7 @@ public class EnhancedBookmarkEditActivity extends EnhancedBookmarkActivityBase {
     private MenuItem mDeleteButton;
 
     private OfflineButtonType mOfflineButtonType = OfflineButtonType.NONE;
+    private OfflinePageModelObserver mOfflinePageModelObserver;
 
     private BookmarkModelObserver mBookmarkModelObserver = new BookmarkModelObserver() {
         @Override
@@ -129,6 +131,16 @@ public class EnhancedBookmarkEditActivity extends EnhancedBookmarkActivityBase {
         });
 
         if (OfflinePageBridge.isEnabled()) {
+            mOfflinePageModelObserver = new OfflinePageModelObserver() {
+                @Override
+                public void offlinePageDeleted(BookmarkId bookmarkId) {
+                    if (mBookmarkId.equals(bookmarkId)) {
+                        updateOfflineSection();
+                    }
+                }
+            };
+
+            mEnhancedBookmarksModel.getOfflinePageBridge().addObserver(mOfflinePageModelObserver);
             // Make offline page section visible and find controls.
             findViewById(R.id.offline_page_group).setVisibility(View.VISIBLE);
             getIntent().setExtrasClassLoader(WebContents.class.getClassLoader());
@@ -208,6 +220,10 @@ public class EnhancedBookmarkEditActivity extends EnhancedBookmarkActivityBase {
     @Override
     protected void onDestroy() {
         recordOfflineButtonAction(false);
+        if (OfflinePageBridge.isEnabled()) {
+            mEnhancedBookmarksModel.getOfflinePageBridge().removeObserver(
+                    mOfflinePageModelObserver);
+        }
         mEnhancedBookmarksModel.removeObserver(mBookmarkModelObserver);
         mEnhancedBookmarksModel.destroy();
         mEnhancedBookmarksModel = null;
@@ -220,6 +236,7 @@ public class EnhancedBookmarkEditActivity extends EnhancedBookmarkActivityBase {
 
         OfflinePageItem offlinePage = mEnhancedBookmarksModel.getOfflinePageBridge()
                 .getPageByBookmarkId(mBookmarkId);
+        mEnhancedBookmarksModel.getOfflinePageBridge().checkOfflinePageMetadata();
         if (offlinePage != null) {
             // Offline page exists. Show information and button to remove.
             offlinePageInfoTextView.setText(getString(R.string.bookmark_offline_page_size,