Bug 834414 - Stop holding on to a content resolver in Tab, which leaks the Activity instance it is associated with. r=bnicholson

mobile/android/base/Tabs.java

@@ -16,6 +16,7 @@ import android.accounts.AccountManager;
 import android.accounts.OnAccountsUpdateListener;
 import android.content.ContentResolver;
 import android.content.Intent;
+import android.database.ContentObserver;
 import android.net.Uri;
 import android.util.Log;
 import android.widget.Toast;
@@ -55,6 +56,7 @@ public class Tabs implements GeckoEventListener {
     private static AtomicInteger sTabId = new AtomicInteger(0);
 
     private GeckoApp mActivity;
+    private ContentObserver mContentObserver;
 
     private Tabs() {
         registerEventListener("SessionHistory:New");
@@ -82,6 +84,9 @@ public class Tabs implements GeckoEventListener {
                 persistAllTabs();
             }
         }, GeckoAppShell.getHandler(), false);
+        if (mContentObserver != null) {
+            BrowserDB.registerBookmarkObserver(getContentResolver(), mContentObserver);
+        }
     }
 
     public void detachFromActivity(GeckoApp activity) {
@@ -89,13 +94,31 @@ public class Tabs implements GeckoEventListener {
             mAccountManager.removeOnAccountsUpdatedListener(mAccountListener);
             mAccountListener = null;
         }
+        if (mContentObserver != null) {
+            BrowserDB.unregisterContentObserver(getContentResolver(), mContentObserver);
+        }
     }
 
     public int getCount() {
         return mTabs.size();
     }
 
+    private void lazyRegisterBookmarkObserver() {
+        if (mContentObserver == null) {
+            mContentObserver = new ContentObserver(null) {
+                public void onChange(boolean selfChange) {
+                    for (Tab tab : mTabs.values()) {
+                        tab.updateBookmark();
+                    }
+                }
+            };
+            BrowserDB.registerBookmarkObserver(getContentResolver(), mContentObserver);
+        }
+    }
+
     private Tab addTab(int id, String url, boolean external, int parentId, String title, boolean isPrivate) {
+        lazyRegisterBookmarkObserver();
+
         final Tab tab = isPrivate ? new PrivateTab(id, url, external, parentId, title) :
                                     new Tab(id, url, external, parentId, title);
         mTabs.put(id, tab);