Add callout for the tab switcher button

chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherCallout.java

Index: chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherCallout.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherCallout.java b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherCallout.java
new file mode 100644
index 0000000000000000000000000000000000000000..a5719f2392fee09bb210ec718142a4bec870e111
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherCallout.java
@@ -0,0 +1,96 @@
+// 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.toolbar;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.os.Build;
+import android.os.Handler;
+import android.preference.PreferenceManager;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.View.OnClickListener;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.widget.TextBubble;
+
+/**
+ * Draws a bubble pointing upward at the tab switcher button.
+ */
+public class TabSwitcherCallout extends TextBubble {
+    public static final String PREF_NEED_TO_SHOW_TAB_SWITCHER_CALLOUT =
+            "org.chromium.chrome.browser.toolbar.NEED_TO_SHOW_TAB_SWITCHER_CALLOUT";
+
+    private static final int TAB_SWITCHER_CALLOUT_DISMISS_MS = 10000;
+    private static final float Y_OVERLAP_PERCENTAGE = 0.33f;
+
+    private static Boolean sIsTabSwitcherCalloutNecessary = null;
+
+    /**
+     * Show the TabSwitcherCallout, if necessary.
+     * @param context           Context to draw resources from.
+     * @param tabSwitcherButton Button that triggers the tab switcher.
+     * @return TabSwitcherCallout if one was shown, null otherwise.
+     */
+    public static TabSwitcherCallout showIfNecessary(Context context, View tabSwitcherButton) {
+        if (!isTabSwitcherCalloutNecessary(context)) return null;
+        setIsTabSwitcherCalloutNecessary(context, false);
+
+        final TabSwitcherCallout callout = new TabSwitcherCallout(context);
+        callout.show(tabSwitcherButton);
+
+        // Dismiss the popup automatically after a delay.
+        new Handler().postDelayed(new Runnable() {
+            @Override
+            public void run() {
+                callout.dismiss();
+            }
+        }, TAB_SWITCHER_CALLOUT_DISMISS_MS);
+
+        return callout;
+    }
+
+    @Override
+    protected View createContent(Context context) {
+        View content = LayoutInflater.from(context).inflate(R.layout.tab_switcher_callout, null);
+
+        // Dismiss the popup when the "OK" button is clicked.
+        View okButton = content.findViewById(R.id.confirm_button);
+        okButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                dismiss();
+            }
+        });
+
+        return content;
+    }
+
+    /** @return Whether or not the tab switcher button callout needs to be shown. */
+    public static boolean isTabSwitcherCalloutNecessary(Context context) {
+        if (sIsTabSwitcherCalloutNecessary == null) {
+            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+            sIsTabSwitcherCalloutNecessary =
+                    prefs.getBoolean(PREF_NEED_TO_SHOW_TAB_SWITCHER_CALLOUT, false);
+        }
+        return sIsTabSwitcherCalloutNecessary;
+    }
+
+    /**
+     * Sets whether the tab switcher callout should be shown when the browser starts up.
+     */
+    public static void setIsTabSwitcherCalloutNecessary(Context context, boolean shouldShow) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        prefs.edit().putBoolean(PREF_NEED_TO_SHOW_TAB_SWITCHER_CALLOUT, shouldShow).apply();
+        sIsTabSwitcherCalloutNecessary = shouldShow;
+    }
+
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    private TabSwitcherCallout(Context context) {
+        super(context, Y_OVERLAP_PERCENTAGE);
+        setAnimationStyle(R.style.TabSwitcherCalloutAnimation);
+    }
+}