[ios] BubbleViewController and BubbleView stubs.

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

+// 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.
+
+#import "ios/chrome/browser/ui/bubble/bubble_view.h"
+
+#include "base/logging.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface BubbleView ()
+// Label containing the text displayed on the bubble.
+@property(nonatomic, readonly, weak) UILabel* label;

[edchin, 2017/07/08 07:58:26]

Please remove the "readonly" attribute here. 
I previously commented on this same line in this CL
but it seems to have reappeared in this latest patch.
Here's a link that explains more about the property attributes:
https://useyourloaf.com/blog/default-property-attributes-with-arc/ 

[helenlyang, 2017/07/10 17:15:23]

Done.

+@end
+
+@implementation BubbleView
+
+@synthesize label = _label;
+
+- (instancetype)initWithText:(NSString*)text
+                   direction:(BubbleArrowDirection)arrowDirection
+                   alignment:(BubbleAlignment)alignment {
+  self = [super initWithFrame:CGRectZero];
+  return self;
+}
+
+#pragma mark - UIView overrides
+
+// Overriding sizeThatFits allows BubbleViewController and

[gchatz, 2017/07/08 00:46:22]

I think the standard practice is to use an imperative, like:
Override sizeThatFits so that ...

[helenlyang, 2017/07/10 17:15:22]

Done.

+// BubbleViewController's parent to appropriately set the BubbleView's size.

[edchin, 2017/07/08 07:58:26]

This class should not know about BubbleViewController. 
Please refrain from commenting about BubbleVC.

[helenlyang, 2017/07/10 17:15:23]

Done.

+- (CGSize)sizeThatFits:(CGSize)size {
+  NOTIMPLEMENTED();
+  return CGSizeZero;
+}
+
+@end