[Mac][MC] Adjust the size of the status item view based on the unread count.

ui/message_center/cocoa/status_item_view_unittest.mm

 // Copyright (c) 2013 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 "ui/message_center/cocoa/status_item_view.h"
 
 #include "base/memory/scoped_nsobject.h"
 #import "ui/base/test/ui_cocoa_test_helper.h"
 
 class StatusItemViewTest : public ui::CocoaTest {
@@ skipping 36 matching lines @@
   EXPECT_TRUE(got_callback);
   [view_ rightMouseUp:nil];
 
   got_callback = NO;
   [view_ otherMouseDown:nil];
   EXPECT_TRUE(got_callback);
   [view_ otherMouseUp:nil];
 }
 
 TEST_F(StatusItemViewTest, UnreadCount) {
+  CGFloat initial_width = NSWidth([view_ frame]);
+
+  CGFloat width = initial_width;
   [view_ setUnreadCount:2];
   [view_ display];
+  EXPECT_GT(NSWidth([view_ frame]), width);
+  width = NSWidth([view_ frame]);
+
   [view_ setUnreadCount:10];
   [view_ display];
+  EXPECT_GT(NSWidth([view_ frame]), width);
+  width = NSWidth([view_ frame]);
+
+  CGFloat max_width = width;
+
   [view_ setUnreadCount:0];
   [view_ display];
+  EXPECT_LT(NSWidth([view_ frame]), width);
+  width = NSWidth([view_ frame]);
+  EXPECT_CGFLOAT_EQ(width, initial_width);
+
   [view_ setUnreadCount:1000];
   [view_ display];
+  EXPECT_GT(NSWidth([view_ frame]), width);
+  width = NSWidth([view_ frame]);
+  EXPECT_CGFLOAT_EQ(width, max_width);
 }
 
 TEST_F(StatusItemViewTest, Highlight) {
   [view_ setHighlight:YES];
   [view_ display];
   [view_ setHighlight:NO];
   [view_ display];
 }
 
 TEST_F(StatusItemViewTest, HighlightAndMouseEvent) {
   [view_ mouseDown:nil];
   [view_ display];
   [view_ setHighlight:YES];
   [view_ display];
   [view_ mouseUp:nil];
   [view_ display];
   [view_ setHighlight:NO];
   [view_ display];
 }