Widget opacity goes from 0 to 1, not 0 to 255.

ui/message_center/views/toast_contents_view.cc

 // 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.
 
 #include "ui/message_center/views/toast_contents_view.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 181 matching lines @@
     const gfx::Animation* animation) {
   if (is_closing_ && closing_animation_ == animation && GetWidget()) {
     views::Widget* widget = GetWidget();
 
     // TODO(dewittj): This is a workaround to prevent a nasty bug where
     // closing a transparent widget doesn't actually remove the window,
     // causing entire areas of the screen to become unresponsive to clicks.
     // See crbug.com/243469
     widget->Hide();
 #if defined(OS_WIN)
-    widget->SetOpacity(0xFF);
+    widget->SetOpacity(1.f);
 #endif
 
     widget->Close();
   }
 
   // This cannot be called before GetWidget()->Close(). Decrementing defer count
   // will invoke update, which may invoke another close animation with
   // incrementing defer counter. Close() after such process will cause a
   // mismatch between increment/decrement. See crbug.com/238477
   if (collection_)
     collection_->DecrementDeferCounter();
 }
 
 // gfx::AnimationDelegate
 void ToastContentsView::AnimationProgressed(const gfx::Animation* animation) {
   if (animation == bounds_animation_.get()) {
     gfx::Rect current(animation->CurrentValueBetween(
         animated_bounds_start_, animated_bounds_end_));
     GetWidget()->SetBounds(current);
   } else if (animation == fade_animation_.get()) {
-    unsigned char opacity =
-        static_cast<unsigned char>(fade_animation_->GetCurrentValue() * 255);
-    GetWidget()->SetOpacity(opacity);
+    GetWidget()->SetOpacity(
+        static_cast<float>(fade_animation_->GetCurrentValue()));
   }
 }
 
 void ToastContentsView::AnimationEnded(const gfx::Animation* animation) {
   OnBoundsAnimationEndedOrCancelled(animation);
 }
 
 void ToastContentsView::AnimationCanceled(
     const gfx::Animation* animation) {
   OnBoundsAnimationEndedOrCancelled(animation);
@@ skipping 145 matching lines @@
 }
 
 gfx::Rect ToastContentsView::GetClosedToastBounds(gfx::Rect bounds) {
   return gfx::Rect(bounds.x() + bounds.width() - kClosedToastWidth,
                    bounds.y(),
                    kClosedToastWidth,
                    bounds.height());
 }
 
 }  // namespace message_center