Converts Widget::SetOpacity from char to float

ui/views/widget/native_widget_mac.h

 // Copyright 2014 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.
 
 #ifndef UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_
 #define UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_
 
 #include "base/macros.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/widget/native_widget_private.h"
@@ skipping 89 matching lines @@
   void SetAlwaysOnTop(bool always_on_top) override;
   bool IsAlwaysOnTop() const override;
   void SetVisibleOnAllWorkspaces(bool always_visible) override;
   void Maximize() override;
   void Minimize() override;
   bool IsMaximized() const override;
   bool IsMinimized() const override;
   void Restore() override;
   void SetFullscreen(bool fullscreen) override;
   bool IsFullscreen() const override;
-  void SetOpacity(unsigned char opacity) override;
+  void SetOpacity(float opacity) override;
   void FlashFrame(bool flash_frame) override;
   void RunShellDrag(View* view,
                     const ui::OSExchangeData& data,
                     const gfx::Point& location,
                     int operation,
                     ui::DragDropTypes::DragEventSource source) override;
   void SchedulePaintInRect(const gfx::Rect& rect) override;
   void SetCursor(gfx::NativeCursor cursor) override;
   bool IsMouseEventsEnabled() const override;
   void ClearNativeFocus() override;
@@ skipping 33 matching lines @@
 
   // Internal name.
   std::string name_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetMac);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_