Download Home : Dont show headers when showing prefetch tab

This CL adds the following changes:
1 - On prefetch tab, date headers and section headers are not shown.
2 - On chips other than type ALL, section headers are not shown.

Bug: 866307
Change-Id: I0f184f31a80fc1d4e5defab780f430590532f517
Reviewed-on: https://chromium-review.googlesource.com/1162517
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581107}

chrome/android/java/src/org/chromium/chrome/browser/download/home/list/DateOrderedListMediator.java

@@ -141,6 +141,7 @@ class DateOrderedListMediator {
      * @see TypeOfflineItemFilter#onFilterSelected(int)
      */
     public void onFilterTypeSelected(@FilterType int filter) {
+        mListMutator.onFilterTypeSelected(filter);
         try (AnimationDisableClosable closeable = new AnimationDisableClosable()) {
             mTypeFilter.onFilterSelected(filter);
         }

chrome/android/java/src/org/chromium/chrome/browser/download/home/list/DateOrderedListMutator.java

@@ -37,9 +37,12 @@ import java.util.TreeMap;
 class DateOrderedListMutator implements OfflineItemFilterObserver {
     private final ListItemModel mModel;
 
-    private Map<Date, DateGroup> mDateGroups =
+    private final Map<Date, DateGroup> mDateGroups =
             new TreeMap<>((lhs, rhs) -> { return rhs.compareTo(lhs); });
 
+    private boolean mHideAllHeaders;
+    private boolean mHideSectionHeaders;
+
     /**
      * Creates an DateOrderedList instance that will reflect {@code source}.
      * @param source The source of data for this list.
@@ -51,6 +54,15 @@ class DateOrderedListMutator implements OfflineItemFilterObserver {
         onItemsAdded(source.getItems());
     }
 
+    /**
+     * Called when the selected tab or chip has changed.
+     * @param filter The currently selected filter type.
+     */
+    public void onFilterTypeSelected(@Filters.FilterType int filter) {
+        mHideAllHeaders = filter == Filters.FilterType.PREFETCHED;
+        mHideSectionHeaders = filter != Filters.FilterType.NONE;
+    }
+
     // OfflineItemFilterObserver implementation.
     @Override
     public void onItemsAdded(Collection<OfflineItem> items) {
@@ -121,17 +133,21 @@ class DateOrderedListMutator implements OfflineItemFilterObserver {
             int sectionIndex = 0;
 
             // Add an item for the date header.
-            listItems.add(new DateListItem(CalendarUtils.getStartOfDay(date.getTime())));
+            if (!mHideAllHeaders) {
+                listItems.add(new DateListItem(CalendarUtils.getStartOfDay(date.getTime())));
+            }
 
             // For each section.
             for (Integer filter : dateGroup.sections.keySet()) {
                 Section section = dateGroup.sections.get(filter);
 
                 // Add a section header.
-                SectionHeaderListItem sectionHeaderItem =
-                        new SectionHeaderListItem(filter, date.getTime());
-                sectionHeaderItem.isFirstSectionOfDay = sectionIndex == 0;
-                listItems.add(sectionHeaderItem);
+                if (!mHideSectionHeaders && !mHideAllHeaders) {
+                    SectionHeaderListItem sectionHeaderItem =
+                            new SectionHeaderListItem(filter, date.getTime());
+                    sectionHeaderItem.isFirstSectionOfDay = sectionIndex == 0;
+                    listItems.add(sectionHeaderItem);
+                }
 
                 // Add the items in the section.
                 for (OfflineItem item : section.items.values()) {
@@ -139,14 +155,14 @@ class DateOrderedListMutator implements OfflineItemFilterObserver {
                 }
 
                 // Add a section separator if needed.
-                if (sectionIndex < dateGroup.sections.size() - 1) {
+                if (!mHideAllHeaders && sectionIndex < dateGroup.sections.size() - 1) {
                     listItems.add(new SeparatorViewListItem(date.getTime(), filter));
                 }
                 sectionIndex++;
             }
 
             // Add a date separator if needed.
-            if (dateIndex < mDateGroups.size() - 1) {
+            if (!mHideAllHeaders && dateIndex < mDateGroups.size() - 1) {
                 listItems.add(new SeparatorViewListItem(date.getTime()));
             }
             dateIndex++;