[ios] BubbleViewController and BubbleView stubs.

ios/chrome/browser/ui/bubble/bubble_view.h

+// Copyright 2017 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_BUBBLE_BUBBLE_VIEW_H_
+#define IOS_CHROME_BROWSER_UI_BUBBLE_BUBBLE_VIEW_H_
+
+#import <UIKit/UIKit.h>
+
+// Direction for the bubble to point.
+typedef NS_ENUM(NSInteger, BubbleArrowDirection) {
+  // Bubble is below the target UI element and the arrow is pointing up.
+  BubbleArrowDirectionUp,

[marq (ping after 24h), 2017/07/11 12:21:26]

nit: Provide an initial value for enums:

BubbleArrowDirectionUp = 0,

+  // Bubble is above the target UI element and the arrow is pointing down.
+  BubbleArrowDirectionDown,
+};
+
+// Alignment of the bubble relative to the arrow.
+typedef NS_ENUM(NSInteger, BubbleAlignment) {
+  BubbleAlignmentLeading,
+  BubbleAlignmentCenter,
+  BubbleAlignmentTrailing,
+};
+
+// Speech bubble shaped view that displays a message.
+@interface BubbleView : UIView
+
+// Initializes with the given text, direction that the bubble should point, and
+// alignment of the bubble.
+- (instancetype)initWithText:(NSString*)text
+                   direction:(BubbleArrowDirection)arrowDirection
+                   alignment:(BubbleAlignment)alignment
+    NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)initWithFrame:(CGRect)frame NS_UNAVAILABLE;
+
+- (instancetype)initWithCoder:(NSCoder*)aDecoder NS_UNAVAILABLE;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_BUBBLE_BUBBLE_VIEW_H_