Add Unit Tests to SnackbarCollection

chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarCollection.java

Index: chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarCollection.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarCollection.java b/chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarCollection.java
new file mode 100644
index 0000000000000000000000000000000000000000..613b2c8de98a6d0d6e0c245460ec4a436ff5461c
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarCollection.java
@@ -0,0 +1,130 @@
+// Copyright 2016 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.snackbar;
+
+import org.chromium.chrome.browser.snackbar.SnackbarManager.SnackbarController;
+
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * A data structure that holds all the {@link Snackbar}s managed by {@link SnackbarManager}.
+ */
+class SnackbarCollection {
+    private Deque<Snackbar> mStack = new LinkedList<>();
+    private Queue<Snackbar> mQueue = new LinkedList<>();
+
+    /**
+     * Adds a new snackbar to the collection. If the new snackbar is of
+     * {@link Snackbar#TYPE_ACTION} and current snackbar is of
+     * {@link Snackbar#TYPE_NOTIFICATION}, the current snackbar will be removed from the
+     * collection immediately.
+     */
+    void add(Snackbar snackbar) {
+        if (snackbar.isTypeAction()) {
+            if (getCurrent() != null && !getCurrent().isTypeAction()) {
+                removeCurrent(false);
+            }
+            mStack.push(snackbar);
+        } else {
+            mQueue.offer(snackbar);
+        }
+    }
+
+    /**
+     * Removes the current snackbar from the collection after the user has clicked on the action
+     * button.
+     */
+    Snackbar removeCurrentDueToAction() {
+        return removeCurrent(true);
+    }
+
+    private Snackbar removeCurrent(boolean isAction) {
+        Snackbar current = !mStack.isEmpty() ? mStack.pop() : mQueue.poll();
+        if (current != null) {
+            SnackbarController controller = current.getController();
+            if (isAction) controller.onAction(current.getActionData());
+            else controller.onDismissNoAction(current.getActionData());
+        }
+        return current;
+    }
+
+    /**
+     * @return The snackbar that is currently displayed.
+     */
+    Snackbar getCurrent() {
+        return !mStack.isEmpty() ? mStack.peek() : mQueue.peek();
+    }
+
+    boolean isEmpty() {
+        return mStack.isEmpty() && mQueue.isEmpty();
+    }
+
+    void clear() {
+        while (!isEmpty()) {
+            removeCurrent(false);
+        }
+    }
+
+    void removeCurrentDueToTimeout() {
+        removeCurrent(false);
+        Snackbar current;
+        while ((current = getCurrent()) != null && current.isTypeAction()) {
+            removeCurrent(false);
+        }
+    }
+
+    boolean removeMatchingSnackbars(SnackbarController controller) {
+        boolean snackbarRemoved = false;
+        Iterator<Snackbar> iter = mStack.iterator();
+        while (iter.hasNext()) {
+            Snackbar snackbar = iter.next();
+            if (snackbar.getController() == controller) {
+                iter.remove();
+                snackbarRemoved = true;
+            }
+        }
+        iter = mQueue.iterator();
+        while (iter.hasNext()) {
+            Snackbar snackbar = iter.next();
+            if (snackbar.getController() == controller) {
+                iter.remove();
+                snackbarRemoved = true;
+            }
+        }
+        return snackbarRemoved;
+    }
+
+    boolean removeMatchingSnackbars(SnackbarController controller, Object data) {
+        boolean snackbarRemoved = false;
+        Iterator<Snackbar> iter = mStack.iterator();
+        while (iter.hasNext()) {
+            Snackbar snackbar = iter.next();
+            if (snackbar.getController() == controller
+                    && objectsAreEqual(snackbar.getActionData(), data)) {
+                iter.remove();
+                snackbarRemoved = true;
+            }
+        }
+        iter = mQueue.iterator();
+        while (iter.hasNext()) {
+            Snackbar snackbar = iter.next();
+            if (snackbar.getController() == controller
+                    && objectsAreEqual(snackbar.getActionData(), data)) {
+                iter.remove();
+                snackbarRemoved = true;
+            }
+        }
+        return snackbarRemoved;
+    }
+
+    private static boolean objectsAreEqual(Object a, Object b) {
+        if (a == null && b == null) return true;
+        if (a == null || b == null) return false;
+        return a.equals(b);
+    }
+}