More boring fade in/out animations for constrained windows

chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm

Index: chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm
diff --git a/chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm b/chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm
index ab67fc6804b9dea5550e579b8a0dac4039b480d0..a5128cacf57a6924afd64b7ccd7fcb845105a07b 100644
--- a/chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm
+++ b/chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.mm
@@ -7,6 +7,9 @@
 #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 {
@@ -17,20 +20,29 @@
 }
 
 - (void)showSheetForWindow:(NSWindow*)window {
-  base::scoped_nsobject<NSAnimation> animation(
-      [[ConstrainedWindowAnimationShow alloc] initWithWindow:customWindow_]);
   [window addChildWindow:customWindow_
                  ordered:NSWindowAbove];
   [self unhideSheet];
   [self updateSheetPosition];
   [customWindow_ makeKeyAndOrderFront:nil];
-  [animation startAnimation];
+  [customWindow_ setAlphaValue:0.0];
+  [[NSAnimationContext currentContext] setDuration:kAnimationDuration];
+  [[customWindow_ animator] setAlphaValue:1.0];
 }
 
 - (void)closeSheetWithAnimation:(BOOL)withAnimation {
   if (withAnimation) {
+    // Use a blocking animation, rather than -[NSWindow animator].
+    NSArray* animationArray = @[
+      @{
+        NSViewAnimationTargetKey : customWindow_,
+        NSViewAnimationEffectKey : NSViewAnimationFadeOutEffect,
+      }
+    ];
     base::scoped_nsobject<NSAnimation> animation(
-        [[ConstrainedWindowAnimationHide alloc] initWithWindow:customWindow_]);
+        [[NSViewAnimation alloc] initWithViewAnimations:animationArray]);
+    [animation setDuration:kAnimationDuration];
+    [animation setAnimationBlockingMode:NSAnimationBlocking];
     [animation startAnimation];
   }