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chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadItemSelectionDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadItemSelectionDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadItemSelectionDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadItemSelectionDelegate.java
new file mode 100644
index 0000000000000000000000000000000000000000..5ae4314d804cbdcea63a563f5971378bc7c85a19
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadItemSelectionDelegate.java
@@ -0,0 +1,75 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.download.ui;
+
+import org.chromium.chrome.browser.download.ui.DownloadHistoryAdapter.SubsectionHeader;
+import org.chromium.chrome.browser.widget.selection.SelectionDelegate;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Separately maintains the selected state of the {@link SubsectionHeader}s in addition to the other
+ * selected items.
+ */
+public class DownloadItemSelectionDelegate extends SelectionDelegate<DownloadHistoryItemWrapper> {
+    private final Set<SubsectionHeader> mSelectedHeaders = new HashSet<>();
+
+    @Override
+    public boolean isSelectionEnabled() {

[shaktisahu, 2017/03/09 06:03:33]

Removing this as suggested in Theresa's prior comment. We shouldn't be counting
the headers towards selected state as they are implicitly selected/deselected
based on the state of the associated items.

+        return !mSelectedHeaders.isEmpty() || super.isSelectionEnabled();
+    }
+
+    /**
+     * True if the header is currently selected. False otherwise.
+     * @param header The given header.
+     * @return Whether the header is selected.
+     */
+    public boolean isHeaderSelected(SubsectionHeader header) {
+        return mSelectedHeaders.contains(header);
+    }
+
+    @Override
+    public void clearSelection() {
+        mSelectedHeaders.clear();
+        super.clearSelection();
+    }
+
+    /**
+     * Toggles selection for a given subsection and sets the associated items to the correct
+     * selection state.
+     * @param header The header for the subsection being toggled.
+     * @return True if the header is selected after the toggle, false otherwise.
+     */
+    public boolean toggleSelectionForSubsection(SubsectionHeader header) {
+        boolean newSelectedState = !isHeaderSelected(header);
+        for (DownloadHistoryItemWrapper item : header.getItems()) {
+            if (newSelectedState != isItemSelected(item)) {
+                toggleSelectionForItem(item);
+            }
+        }
+
+        return setSelectionForHeader(header, newSelectedState);
+    }
+
+    /**
+     * Sets the selection state for a given header. Doesn't affect the associated items. This method
+     * is supposed to be called if the header needs to be toggled as a result of selecting or
+     * deselecting one of the associated items. In case of a long press on the header, don't call
+     * this method, call toggleSelectionForSubsection instead directly.

[Theresa, 2017/03/08 16:08:17]

nit: the end of this should be "call {@link toggleSelectionForSubsection()}
instead"

[shaktisahu, 2017/03/09 06:03:33]

Done.

+     * @param header The given {@link SubsectionHeader}.
+     * @param selected The new selected state.
+     * @return Whether the header was successfully selected.

[Theresa, 2017/03/08 16:08:17]

nit: This returns whether the header is selected. If this is called with
selected = false and it returns false, then I would consider that "successful".

[shaktisahu, 2017/03/09 06:03:33]

Done.

+     */
+    public boolean setSelectionForHeader(SubsectionHeader header, boolean selected) {
+        if (selected) {
+            mSelectedHeaders.add(header);
+        } else {
+            mSelectedHeaders.remove(header);
+        }
+
+        return isHeaderSelected(header);
+    }
+}