[iOS] Add experimental new keyboard accessory view.

ios/chrome/browser/ui/fancy_ui/colored_button.h

+// 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.
+
+#ifndef IOS_CHROME_BROWSER_UI_FANCY_UI_COLORED_BUTTON_H_
+#define IOS_CHROME_BROWSER_UI_FANCY_UI_COLORED_BUTTON_H_
+
+#import <UIKit/UIKit.h>
+
+// Subclass of UIButton whose tint and background colors can changes depending
+// on the button's state.
+// If a color is not specified for a state, uses the UIControlStateNormal
+// value. If the UIControlStateNormal value is not set, defaults to the system's
+// value.
+@interface ColoredButton : UIButton
+
+// Sets the tint color of a button to use for the specified state.
+// Currently only supports |UIControlStateNormal| and
+// |UIControlStateHighlighted|.
+- (void)setTintColor:(UIColor*)color forState:(UIControlState)state;
+
+// Sets the background color of a button to use for the specified state.
+// Currently only supports |UIControlStateNormal| and
+// |UIControlStateHighlighted|.
+- (void)setBackgroundColor:(UIColor*)color forState:(UIControlState)state;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_FANCY_UI_COLORED_BUTTON_H_