mac: Remove uses of a CoreGraphics private API that causes WindowServer crashes.

chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.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.
 
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 #import "ui/base/cocoa/constrained_window/constrained_window_animation.h"
 
+// Length of the animation in seconds.
+const NSTimeInterval kAnimationDuration = 0.18;
+
 @implementation CustomConstrainedWindowSheet
 
 - (id)initWithCustomWindow:(NSWindow*)customWindow {
   if ((self = [super init])) {
     customWindow_.reset([customWindow retain]);
   }
   return self;
 }
 
+- (void)setUseSimpleAnimations:(BOOL)simpleAnimations {
+  useSimpleAnimations_ = simpleAnimations;
+}
+
 - (void)showSheetForWindow:(NSWindow*)window {
-  base::scoped_nsobject<NSAnimation> animation(
-      [[ConstrainedWindowAnimationShow alloc] initWithWindow:customWindow_]);
+  base::scoped_nsobject<NSAnimation> animation;
+  if (!useSimpleAnimations_) {
+    animation.reset(
+        [[ConstrainedWindowAnimationShow alloc] initWithWindow:customWindow_]);
+  }
   [window addChildWindow:customWindow_
                  ordered:NSWindowAbove];
   [self unhideSheet];
   [self updateSheetPosition];
   [customWindow_ makeKeyAndOrderFront:nil];
-  [animation startAnimation];
+
+  if (useSimpleAnimations_) {
+    [customWindow_ setAlphaValue:0.0];
+    [[NSAnimationContext currentContext] setDuration:kAnimationDuration];

[tapted, 2016/03/15 00:39:40]

I think we need a

[NSAnimationContext beginGrouping];

before this

and a 

[NSAnimationContext endGrouping];

after the setAlphaValue.

I guess the duration might "leak" out to other animations otherwise.

[erikchen, 2016/03/15 00:52:25]

Done.

+    [[customWindow_ animator] setAlphaValue:1.0];
+  } else {
+    [animation startAnimation];
+  }
 }
 
 - (void)closeSheetWithAnimation:(BOOL)withAnimation {
   if (withAnimation) {
-    base::scoped_nsobject<NSAnimation> animation(
-        [[ConstrainedWindowAnimationHide alloc] initWithWindow:customWindow_]);
+    base::scoped_nsobject<NSAnimation> animation;
+    if (useSimpleAnimations_) {
+      // Use a blocking animation, rather than -[NSWindow animator].
+      NSArray* animationArray = @[ @{
+        NSViewAnimationTargetKey : customWindow_,
+        NSViewAnimationEffectKey : NSViewAnimationFadeOutEffect,
+      } ];
+      animation.reset(
+          [[NSViewAnimation alloc] initWithViewAnimations:animationArray]);
+      [animation setDuration:kAnimationDuration];
+      [animation setAnimationBlockingMode:NSAnimationBlocking];
+    } else {
+      animation.reset([[ConstrainedWindowAnimationHide alloc]
+          initWithWindow:customWindow_]);
+    }
     [animation startAnimation];
   }
 
   [[customWindow_ parentWindow] removeChildWindow:customWindow_];
   [customWindow_ close];
 }
 
 - (void)hideSheet {
   // Hide the sheet window, and any of its direct child windows, by setting the
   // alpha to 0. This technique is used instead of -orderOut: because that may
@@ skipping 31 matching lines @@
 
 - (void)resizeWithNewSize:(NSSize)size {
   // NOOP
 }
 
 - (NSWindow*)sheetWindow {
   return customWindow_;
 }
 
 @end