Upstreaming AppMenu.

chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuButtonHelper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuButtonHelper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuButtonHelper.java b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuButtonHelper.java
new file mode 100644
index 0000000000000000000000000000000000000000..524cf5493111c020d6def3f6922815429dfc4570
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuButtonHelper.java
@@ -0,0 +1,108 @@
+// Copyright 2013 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.appmenu;
+
+import android.view.GestureDetector;
+import android.view.GestureDetector.SimpleOnGestureListener;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.View.OnTouchListener;
+
+import org.chromium.chrome.browser.UmaBridge;
+
+/**
+ * A helper class for a menu button to decide when to show the app menu and forward touch
+ * events.
+ *
+ * Simply construct this class and pass the class instance to a menu button as TouchListener.
+ * Then this class will handle everything regarding showing app menu for you.
+ */
+public class AppMenuButtonHelper extends SimpleOnGestureListener implements OnTouchListener {
+    private final View mMenuButton;
+    private final AppMenuHandler mMenuHandler;
+    private final GestureDetector mAppMenuGestureDetector;
+    private boolean mSeenFirstScrollEvent;
+    private Runnable mOnAppMenuShownListener;
+
+    /**
+     * @param menuButton  Menu button instance that will trigger the app menu.
+     * @param menuHandler MenuHandler implementation that can show and get the app menu.
+     */
+    public AppMenuButtonHelper(View menuButton, AppMenuHandler menuHandler) {
+        mMenuButton = menuButton;
+        mMenuHandler = menuHandler;
+        mAppMenuGestureDetector = new GestureDetector(menuButton.getContext(), this);
+        mAppMenuGestureDetector.setIsLongpressEnabled(false);
+    }
+
+    /**
+     * @param onAppMenuShownListener This is called when the app menu is shown by this class.
+     */
+    public void setOnAppMenuShownListener(Runnable onAppMenuShownListener) {
+        mOnAppMenuShownListener = onAppMenuShownListener;
+    }
+
+    /**
+     * Shows the app menu if it is not already shown.
+     * @param startDragging Whether dragging is started.
+     * @return Whether or not if the app menu is successfully shown.
+     */
+    private boolean showAppMenu(boolean startDragging) {
+        if (!mMenuHandler.isAppMenuShowing() &&
+                mMenuHandler.showAppMenu(mMenuButton, false, startDragging)) {
+            UmaBridge.usingMenu(false, startDragging);
+            if (mOnAppMenuShownListener != null) {
+                mOnAppMenuShownListener.run();
+            }
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public boolean onDown(MotionEvent e) {
+        mSeenFirstScrollEvent = false;
+        mMenuButton.setPressed(true);
+
+        return true;
+    }
+
+    @Override
+    public boolean onSingleTapUp(MotionEvent e) {
+        // A single tap shows the app menu, but dragging disabled.
+        return showAppMenu(false);
+    }
+
+    @Override
+    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
+        if (mSeenFirstScrollEvent) return false;
+        mSeenFirstScrollEvent = true;
+
+        // If the scrolling direction is roughly down on the first onScroll detection,
+        // we consider it as dragging start, so shows the app menu. Otherwise, we
+        // don't show menu so that toolbar horizontal swiping can happen.
+        return -distanceY >= Math.abs(distanceX) && showAppMenu(true);
+    }
+
+    @Override
+    public boolean onTouch(View view, MotionEvent event) {
+        if (event.getActionMasked() == MotionEvent.ACTION_CANCEL ||
+                event.getActionMasked() == MotionEvent.ACTION_UP) {
+            mMenuButton.setPressed(false);
+        }
+
+        // This will take care of showing app menu.
+        boolean isTouchEventConsumed = mAppMenuGestureDetector.onTouchEvent(event);
+
+        // If user starts to drag on this menu button, ACTION_DOWN and all the subsequent touch
+        // events are received here. We need to forward this event to the app menu to handle
+        // dragging correctly.
+        AppMenu menu = mMenuHandler.getAppMenu();
+        if (menu != null && !isTouchEventConsumed) {
+            isTouchEventConsumed |= menu.handleDragging(event);
+        }
+        return isTouchEventConsumed;
+    }
+}