Converts Widget::SetOpacity from char to float

ui/views/widget/desktop_aura/desktop_native_widget_aura.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 "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
@@ skipping 802 matching lines @@
 
 void DesktopNativeWidgetAura::SetFullscreen(bool fullscreen) {
   if (content_window_)
     desktop_window_tree_host_->SetFullscreen(fullscreen);
 }
 
 bool DesktopNativeWidgetAura::IsFullscreen() const {
   return content_window_ && desktop_window_tree_host_->IsFullscreen();
 }
 
-void DesktopNativeWidgetAura::SetOpacity(unsigned char opacity) {
+void DesktopNativeWidgetAura::SetOpacity(float opacity) {
   if (content_window_)
     desktop_window_tree_host_->SetOpacity(opacity);
 }
 
 void DesktopNativeWidgetAura::FlashFrame(bool flash_frame) {
   if (content_window_)
     desktop_window_tree_host_->FlashFrame(flash_frame);
 }
 
 void DesktopNativeWidgetAura::RunShellDrag(
@@ skipping 357 matching lines @@
   if (cursor_reference_count_ == 0) {
     // We are the last DesktopNativeWidgetAura instance, and we are responsible
     // for cleaning up |cursor_manager_|.
     delete cursor_manager_;
     native_cursor_manager_ = NULL;
     cursor_manager_ = NULL;
   }
 }
 
 }  // namespace views