Rename ash desktop_background to wallpaper.

ash/wm/system_wallpaper_controller.cc

Index: ash/wm/system_wallpaper_controller.cc
diff --git a/ash/wm/system_background_controller.cc b/ash/wm/system_wallpaper_controller.cc
similarity index 71%
rename from ash/wm/system_background_controller.cc
rename to ash/wm/system_wallpaper_controller.cc
index 4fb68d468bb3c06981b3da515bb347511a0cd9b1..1e07c2a9789afeb43cb3db9c2468a4330b8276df 100644
--- a/ash/wm/system_background_controller.cc
+++ b/ash/wm/system_wallpaper_controller.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/wm/system_background_controller.h"
+#include "ash/wm/system_wallpaper_controller.h"
 
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
@@ -10,9 +10,8 @@
 
 namespace ash {
 
-SystemBackgroundController::SystemBackgroundController(
-    aura::Window* root_window,
-    SkColor color)
+SystemWallpaperController::SystemWallpaperController(aura::Window* root_window,
+                                                     SkColor color)
     : root_window_(root_window), layer_(new ui::Layer(ui::LAYER_SOLID_COLOR)) {
   root_window_->AddObserver(this);
   layer_->SetColor(color);
@@ -23,15 +22,15 @@ SystemBackgroundController::SystemBackgroundController(
   root_layer->StackAtBottom(layer_.get());
 }
 
-SystemBackgroundController::~SystemBackgroundController() {
+SystemWallpaperController::~SystemWallpaperController() {
   root_window_->RemoveObserver(this);
 }
 
-void SystemBackgroundController::SetColor(SkColor color) {
+void SystemWallpaperController::SetColor(SkColor color) {
   layer_->SetColor(color);
 }
 
-void SystemBackgroundController::OnWindowBoundsChanged(
+void SystemWallpaperController::OnWindowBoundsChanged(
     aura::Window* root,
     const gfx::Rect& old_bounds,
     const gfx::Rect& new_bounds) {