[Android History] Add clear browsing data button and privacy disclaimers

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 003498dfac2ddc17d37384982a0356d1681fc094..1a2f7b128934d3b1663328a55361201713fb6e3d 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
@@ -105,6 +105,12 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
         }
     }
 
+    protected static class HeaderViewHolder extends RecyclerView.ViewHolder {
+        public HeaderViewHolder(View itemView) {
+            super(itemView);
+        }
+    }
+
     /**
      * A bucket of items with the same date.
      */
@@ -116,6 +122,7 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
         private int mIndex;
 
         private boolean mIsSorted;
+        private boolean mIsHeader;

[gone, 2016/12/12 19:14:13]

"Header" is a little too generic because the dates can be considered "headers"
for their sections.  Maybe mIsListHeader?

[Theresa, 2016/12/12 20:09:04]

Done.

 
         public ItemGroup(TimedItem item) {
             mDate = new Date(item.getTimestamp());
@@ -161,11 +168,16 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
          * @return The size of this group.
          */
         public int size() {
+            if (mIsHeader) return 1;
+
             // Plus 1 to account for the date header.
             return mItems.size() + 1;
         }
 
         public TimedItem getItemAt(int index) {
+            // If this is the header, there is only one item.

[gone, 2016/12/12 19:14:13]

What happens if you don't add this clause?  I wonder if it makes sense to change
the constructor to take in a timestamp instead of a TimedItem... if you changed
it so it just took a timestamp and changed the single callsite to immediately
add the TimedItem to the list, then I think you'd be able to avoid storing the
dummy item.

[Theresa, 2016/12/12 20:09:04]

Done.

+            if (mIsHeader) return mItems.get(0);
+
             // 0 is allocated to the date header.
             if (index == 0) return null;
 
@@ -205,8 +217,10 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
 
     public static final int TYPE_DATE = 0;
     public static final int TYPE_NORMAL = 1;
+    public static final int TYPE_HEADER = 2;

[gone, 2016/12/12 19:14:13]

TYPE_HEADER should be 0 since it's at the top.  I don't think anything'll break.

[Theresa, 2016/12/12 20:09:04]

Done.

 
     private int mSize;
+    private boolean mHasHeader;
     private SortedSet<ItemGroup> mGroups = new TreeSet<>(new Comparator<ItemGroup>() {
         @Override
         public int compare(ItemGroup lhs, ItemGroup rhs) {
@@ -221,6 +235,14 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     protected abstract ViewHolder createViewHolder(ViewGroup parent);
 
     /**
+     * Creates a {@link HeaderViewHolder} in the given parent.
+     * @see #onCreateViewHolder(ViewGroup, int)
+     */
+    protected HeaderViewHolder createHeader(ViewGroup parent) {
+        return null;
+    }
+
+    /**
      * Binds the {@link ViewHolder} with the given {@link TimedItem}.
      * @see #onBindViewHolder(ViewHolder, int)
      */
@@ -236,12 +258,6 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
      * Loads a list of {@link TimedItem}s to this adapter. Any previous data will be removed.
      */
     public void loadItems(List<? extends TimedItem> timedItems) {
-        mSize = 0;
-
-        // Unset the positions of all items in the list.
-        for (ItemGroup group : mGroups) group.resetPosition();
-        mGroups.clear();
-
         for (TimedItem timedItem : timedItems) {
             Date date = new Date(timedItem.getTimestamp());
             boolean found = false;
@@ -272,12 +288,40 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     }
 
     /**
+     * Adds a header as the first group in this adapter.
+     */
+    public void addHeader() {
+        ItemGroup header = new ItemGroup(new TimedItem() {
+            @Override
+            public long getTimestamp() {
+                return Long.MAX_VALUE;
+            }
+
+            @Override
+            public long getStableId() {
+                return Long.MAX_VALUE;
+            }
+        });
+        header.mIsHeader = true;
+
+        mGroups.add(header);

[gone, 2016/12/12 19:14:13]

Should assert the size is 0 at this point.  The add() will incorrectly put the
header at the end of the list if stuff is already there.

[Theresa, 2016/12/12 20:09:04]

Done.

+        mSize++;
+        mHasHeader = true;
+    }
+
+    /**
      * Removes all items from this adapter.
+     * @param notifyDataSetChanged Whether to notify that the data set has been changed.
      */
-    public void clear() {
+    public void clear(boolean notifyDataSetChanged) {
         mSize = 0;
+        mHasHeader = false;
+
+        // Unset the positions of all items in the list.
+        for (ItemGroup group : mGroups) group.resetPosition();
         mGroups.clear();
-        notifyDataSetChanged();
+
+        if (notifyDataSetChanged) notifyDataSetChanged();
     }
 
     @Override
@@ -301,7 +345,7 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     @Override
     public final int getItemViewType(int position) {
         Pair<ItemGroup, Integer> pair = getGroupAt(position);
-        return pair.second == 0 ? TYPE_DATE : TYPE_NORMAL;
+        return pair.second == -1 ? TYPE_HEADER : pair.second == 0 ? TYPE_DATE : TYPE_NORMAL;

[gone, 2016/12/12 19:14:13]

1) Should just expand this into a set of conditionals now that there's three
possibilities.

2) Should pull out -1 as a new constant that indicates that it's a header, I
think.

[Theresa, 2016/12/12 20:09:04]

Done. I made TYPE_HEADER = -1.

     }
 
     @Override
@@ -311,6 +355,8 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
                     getTimedItemViewResId(), parent, false));
         } else if (viewType == TYPE_NORMAL) {
             return createViewHolder(parent);
+        } else if (viewType == TYPE_HEADER) {
+            return createHeader(parent);
         }

[gone, 2016/12/12 19:14:13]

Should assert false at this point; I don't know how you could create anything
except those three.

[Theresa, 2016/12/12 20:09:04]

Done.

         return null;
     }
@@ -320,7 +366,7 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
         Pair<Date, TimedItem> pair = getItemAt(position);
         if (holder instanceof DateViewHolder) {
             ((DateViewHolder) holder).setDate(pair.first);
-        } else {
+        } else if (!(holder instanceof HeaderViewHolder)) {

[gone, 2016/12/12 19:14:13]

null !instanceof HeaderViewHolder, so this would likely crash if it ever hit
that.

[Theresa, 2016/12/12 20:09:04]

I don't think that null can be passed in for the holder. If it can be null, we
are are already calling bindViewHolderForTimedItem() because the current else
block doesn't have a conditional.

             bindViewHolderForTimedItem(holder, pair.second);
         }
     }
@@ -336,6 +382,10 @@ public abstract class DateDividedAdapter extends Adapter<RecyclerView.ViewHolder
     protected Pair<ItemGroup, Integer> getGroupAt(int position) {
         // TODO(ianwen): Optimize the performance if the number of groups becomes too large.
         int i = position;

[gone, 2016/12/12 19:14:13]

Move the int i line down to the for loop area.

[Theresa, 2016/12/12 20:09:04]

Done.

+        if (mHasHeader && position == 0) {
+            return new Pair<>(mGroups.first(), -1);
+        }
+
         for (ItemGroup group : mGroups) {
             if (i >= group.size()) {
                 i -= group.size();