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

ash/drag_drop/drag_image_view.cc

 // 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 "ash/drag_drop/drag_image_view.h"
 
 #include "skia/ext/image_operations.h"
 #include "ui/aura/window.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/dip_util.h"
@@ skipping 10 matching lines @@
 Widget* CreateDragWidget(gfx::NativeView context) {
   Widget* drag_widget = new Widget;
   Widget::InitParams params;
   params.type = Widget::InitParams::TYPE_TOOLTIP;
   params.keep_on_top = true;
   params.context = context;
   params.accept_events = false;
   params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
   params.opacity = Widget::InitParams::TRANSLUCENT_WINDOW;
   drag_widget->Init(params);
-  drag_widget->SetOpacity(0xFF);
+  drag_widget->SetOpacity(1.f);
   drag_widget->GetNativeWindow()->set_owned_by_parent(false);
   drag_widget->GetNativeWindow()->SetName("DragWidget");
   SetShadowType(drag_widget->GetNativeView(), wm::SHADOW_TYPE_NONE);
   return drag_widget;
 }
 }
 
 DragImageView::DragImageView(gfx::NativeView context,
                              ui::DragDropTypes::DragEventSource event_source)
     : views::ImageView(),
@@ skipping 50 matching lines @@
     const gfx::Point& position) {
   if (touch_drag_operation_indicator_position_ == position)
     return;
   touch_drag_operation_indicator_position_ = position;
   SchedulePaint();
 }
 
 void DragImageView::SetOpacity(float visibility) {
   DCHECK_GE(visibility, 0.0f);
   DCHECK_LE(visibility, 1.0f);
-  widget_->SetOpacity(static_cast<int>(0xff * visibility));
+  widget_->SetOpacity(visibility);
 }
 
 void DragImageView::OnPaint(gfx::Canvas* canvas) {
   if (GetImage().isNull())
     return;
 
   // |widget_size_| is in DIP. ImageSkia::size() also returns the size in DIP.
   if (GetImage().size() == widget_size_) {
     canvas->DrawImageInt(GetImage(), 0, 0);
   } else {
@@ skipping 65 matching lines @@
   // Enlarge widget if required to fit the drag hint image.
   if (drag_hint_size.width() > widget_size_.width() ||
       drag_hint_size.height() > widget_size_.height()) {
     gfx::Size new_widget_size = widget_size_;
     new_widget_size.SetToMax(drag_hint_size);
     widget_->SetSize(new_widget_size);
   }
 }
 
 }  // namespace ash