Fix OSX 10.12 compilation errors in chrome/browser/ui.

chrome/browser/ui/cocoa/status_bubble_mac.mm

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/ui/cocoa/status_bubble_mac.h"
 
 #include <limits>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 46 matching lines @@
 // passed to +[NSAnimationContext setDuration:] to stop an in-progress
 // animation as quickly as possible.
 const NSTimeInterval kMinimumTimeInterval =
     std::numeric_limits<NSTimeInterval>::min();
 
 // How quickly the status bubble should expand.
 const CGFloat kExpansionDurationSeconds = 0.125;
 
 }  // namespace
 
-@interface StatusBubbleAnimationDelegate : NSObject {
+@interface StatusBubbleAnimationDelegate : NSObject <CAAnimationDelegate> {
  @private
   base::mac::ScopedBlock<void (^)(void)> completionHandler_;
 }
 
 - (id)initWithCompletionHandler:(void (^)(void))completionHandler;
 
-// CAAnimation delegate method
+// CAAnimation delegate methods
+- (void)animationDidStart:(CAAnimation*)animation;
 - (void)animationDidStop:(CAAnimation*)animation finished:(BOOL)finished;
 @end
 
 @implementation StatusBubbleAnimationDelegate
 
 - (id)initWithCompletionHandler:(void (^)(void))completionHandler {
   if ((self = [super init])) {
     completionHandler_.reset(completionHandler, base::scoped_policy::RETAIN);
   }
 
   return self;
 }
 
+- (void)animationDidStart:(CAAnimation*)theAnimation {
+  // CAAnimationDelegate method added on OSX 10.12.
+}
 - (void)animationDidStop:(CAAnimation*)animation finished:(BOOL)finished {
   completionHandler_.get()();
 }
 
 @end
 
 @interface StatusBubbleWindow : NSWindow {
  @private
   void (^completionHandler_)(void);
 }
@@ skipping 749 matching lines @@
     }
   }
 
   // Round the top corners when the bubble is below the parent window.
   if (NSMinY(window_frame) < NSMinY(parent_frame)) {
     corner_flags |= kRoundedTopLeftCorner | kRoundedTopRightCorner;
   }
 
   return corner_flags;
 }