Upstream base implementations of TabModel, TabModelSelector, and TabModelObserver.

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java
new file mode 100644
index 0000000000000000000000000000000000000000..2013fa5a2284a9cbb661cc930d8e431c7662f35d
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/EmptyTabModel.java
@@ -0,0 +1,136 @@
+// Copyright 2014 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.tabmodel;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import org.chromium.chrome.browser.Tab;
+import org.chromium.chrome.browser.profiles.Profile;
+
+/**
+ * Singleton class intended to stub out Tab model before it has been created.
+ */
+public class EmptyTabModel implements TabModel {
+
+    /**
+     * Used to mock TabModel. Application code should use getInstance() to construct an
+     * EmptyTabModel.
+     */
+    @VisibleForTesting
+    protected EmptyTabModel() {}
+
+    // "Initialization on demand holder idiom"
+    private static class LazyHolder {
+        private static final EmptyTabModel INSTANCE = new EmptyTabModel();
+    }
+
+    /**
+     * Get the singleton instance of EmptyTabModel.
+     * @return the instance of EmptyTabModel
+     */
+    public static EmptyTabModel getInstance() {
+        return LazyHolder.INSTANCE;
+    }
+
+    @Override
+    public Profile getProfile() {
+        return null;
+    }
+
+    @Override
+    public boolean isIncognito() {
+        return false;
+    }
+
+    @Override
+    public boolean closeTab(Tab tab) {
+        return false;
+    }
+
+    @Override
+    public Tab getNextTabIfClosed(int id) {
+        return null;
+    }
+
+    @Override
+    public void closeAllTabs() {
+    }
+
+    @Override
+    public int getCount() {
+        // We must return 0 to be consistent with getTab(i)
+        return 0;
+    }
+
+    @Override
+    public Tab getTabAt(int position) {
+        return null;
+    }
+
+    @Override
+    public int indexOf(Tab tab) {
+        return INVALID_TAB_INDEX;
+    }
+
+    @Override
+    public int index() {
+        return INVALID_TAB_INDEX;
+    }
+
+    @Override
+    public void setIndex(int i, TabSelectionType type) {}
+
+    @Override
+    public void moveTab(int id, int newIndex) {}
+
+    @Override
+    public void destroy() {}
+
+    @Override
+    public boolean isClosurePending(int tabId) {
+        return false;
+    }
+
+    @Override
+    public boolean closeTab(Tab tab, boolean animate, boolean uponExit, boolean canUndo) {
+        return false;
+    }
+
+    @Override
+    public TabList getComprehensiveModel() {
+        return this;
+    }
+
+    @Override
+    public void commitAllTabClosures() {
+    }
+
+    @Override
+    public void commitTabClosure(int tabId) {
+    }
+
+    @Override
+    public void cancelTabClosure(int tabId) {
+    }
+
+    @Override
+    public boolean supportsPendingClosures() {
+        return false;
+    }
+
+    @Override
+    public void addTab(Tab tab, int index, TabLaunchType type) {
+        assert false;
+    }
+
+    @Override
+    public void addObserver(TabModelObserver observer) {
+    }
+
+    @Override
+    public void removeObserver(TabModelObserver observer) {
+    }
+
+}