[ios] TextBadgeView interface, implementation, and unit test stubs

ios/chrome/browser/ui/reading_list/text_badge_view.h

Index: ios/chrome/browser/ui/reading_list/text_badge_view.h
diff --git a/ios/chrome/browser/ui/reading_list/text_badge_view.h b/ios/chrome/browser/ui/reading_list/text_badge_view.h
new file mode 100644
index 0000000000000000000000000000000000000000..5179c75a14fb8a175efdbc914cbed8217df2d70c
--- /dev/null
+++ b/ios/chrome/browser/ui/reading_list/text_badge_view.h
@@ -0,0 +1,22 @@
+// 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_READING_LIST_TEXT_BADGE_VIEW_H_
+#define IOS_CHROME_BROWSER_UI_READING_LIST_TEXT_BADGE_VIEW_H_
+
+#import <UIKit/UIKit.h>
+
+// Pill-shaped view that displays white text. The view stretches to fit the

[edchin, 2017/06/28 00:38:23]

We can emulate UILabel's intrinsic content size. 
Basically, a label says the size that it wants to be
but doesn't actually set its own frame. This doesn't 
change the interface, but we can remove the comment
that the view stretches to fit the content. 

Read this link for more information:
https://developer.apple.com/library/content/documentation/UserExperience/Conc...

[helenlyang, 2017/06/28 15:25:07]

Done.

+// display text, and is hidden when the text is the empty string.

[edchin, 2017/06/28 00:38:23]

We can treat the empty string as programmer error. 
Basically, we feel that the programmer is not properly 
using this API if they pass in an empty string. 
Inside the implementation, we can put this line:
DCHECK(text);

[helenlyang, 2017/06/28 15:25:07]

Done (removed this part of the comment).

+@interface TextBadgeView : UIView
+
+// Initialize the text badge with the given frame and display text.
+- (instancetype)initWithFrame:(CGRect)frame displayText:(NSString*)text;

[edchin, 2017/06/28 00:51:14]

We should designate this as the initializer. You can also mark other
initializers as unavailable. 
Here are the ones to mark as unavailable:
- initWithFrame:(CGRect)frame;
- init;

Here's an example:
https://cs.chromium.org/chromium/src/ios/chrome/browser/ui/ntp/new_tab_page_v...

[helenlyang, 2017/06/28 15:25:07]

Done. I also marked initWithCoder: as unavailable.

+
+// Display the text badge view. If |animated| is true, the badge fades in.

[edchin, 2017/06/28 00:38:23]

Let's remove this, since it violates the "dumb view" concept. 

[helenlyang, 2017/06/28 15:25:07]

Done.

+- (void)presentAnimated:(BOOL)animated;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_READING_LIST_TEXT_BADGE_VIEW_H_