[Android History] Add support for removing items

chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java
index eb37562a1c446300257ba9fc258bf7beafff9ce2..003498dfac2ddc17d37384982a0356d1681fc094 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/DateDividedAdapter.java
@@ -108,7 +108,7 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     /**
      * A bucket of items with the same date.
      */
-    private static class ItemGroup {
+    protected static class ItemGroup {
         private final Date mDate;
         private final List<TimedItem> mItems = new ArrayList<>();
 
@@ -128,6 +128,10 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
             mIsSorted = false;
         }
 
+        public void removeItem(TimedItem item) {
+            mItems.remove(item);
+        }
+
         /** Records the position of all the TimedItems in this group, relative to the full list. */
         public void setPosition(int index) {
             assert mIndex == 0;
@@ -329,7 +333,7 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     /**
      * Utility method to traverse all groups and find the {@link ItemGroup} for the given position.
      */
-    private Pair<ItemGroup, Integer> getGroupAt(int position) {
+    protected Pair<ItemGroup, Integer> getGroupAt(int position) {
         // TODO(ianwen): Optimize the performance if the number of groups becomes too large.
         int i = position;
         for (ItemGroup group : mGroups) {
@@ -344,6 +348,13 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     }
 
     /**
+     * @param group The group to remove from the adapter.
+     */
+    protected void removeGroup(ItemGroup group) {
+        mGroups.remove(group);
+    }
+
+    /**
      * Creates a long ID that identifies a particular day in history.
      * @param date Date to process.
      * @return Long that has the day of the year (1-365) in the lowest 16 bits and the year in the