Revert of [Android] Remove hardware menu button dragging support.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
index 0a08ad4a7053e8ed2b6dcb05d1bbc97ec43cd7f4..0091e454ae980bf99cad4290d419fb0759a6ddf5 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
@@ -57,14 +57,12 @@
      * @param startDragging      Whether dragging is started. For example, if the app menu is
      *                           showed by tapping on a button, this should be false. If it is
      *                           showed by start dragging down on the menu button, this should
-     *                           be true. Note that if isByHardwareButton is true, this must
-     *                           be false since we no longer support hardware menu button
-     *                           dragging.
+     *                           be true. Note that if isByHardwareButton is true, this is
+     *                           ignored.
      * @return True, if the menu is shown, false, if menu is not shown, example reasons:
      *         the menu is not yet available to be shown, or the menu is already showing.
      */
     public boolean showAppMenu(View anchorView, boolean isByHardwareButton, boolean startDragging) {
-        assert !(isByHardwareButton && startDragging);
         if (!mDelegate.shouldShowAppMenu() || isAppMenuShowing()) return false;
 
         if (mMenu == null) {
@@ -95,7 +93,7 @@
         mActivity.getWindow().getDecorView().getWindowVisibleDisplayFrame(appRect);
         int rotation = mActivity.getWindowManager().getDefaultDisplay().getRotation();
         mAppMenu.show(wrapper, anchorView, isByHardwareButton, rotation, appRect);
-        mAppMenuDragHelper.onShow(startDragging);
+        mAppMenuDragHelper.onShow(isByHardwareButton, startDragging);
         UmaBridge.menuShow();
         return true;
     }
@@ -159,4 +157,11 @@
             mObservers.get(i).onMenuVisibilityChanged(isVisible);
         }
     }
+
+    /**
+     * TODO(kkimlabs) remove this call.
+     */
+    public void hardwareMenuButtonUp() {
+        if (mAppMenuDragHelper != null) mAppMenuDragHelper.hardwareMenuButtonUp();
+    }
 }