ash: Avoid reloading already-resized custom wallpaper.

ash/desktop_background/desktop_background_controller.cc

Index: ash/desktop_background/desktop_background_controller.cc
diff --git a/ash/desktop_background/desktop_background_controller.cc b/ash/desktop_background/desktop_background_controller.cc
index 2f4e6334ff3f250a068c535943cca452c49d5c6d..6a743e3f7978fe797785db61b06c4d830ddb8034 100644
--- a/ash/desktop_background/desktop_background_controller.cc
+++ b/ash/desktop_background/desktop_background_controller.cc
@@ -120,6 +120,7 @@ class DesktopBackgroundController::WallpaperLoader
 
     if (file_bitmap_) {
       gfx::ImageSkia image = gfx::ImageSkia::CreateFrom1xBitmap(*file_bitmap_);
+      image.MakeThreadSafe();
       wallpaper_resizer_.reset(new WallpaperResizer(
           image, GetMaxDisplaySizeInNative(), file_layout_));
     } else {
@@ -169,7 +170,7 @@ DesktopBackgroundController::~DesktopBackgroundController() {
 
 gfx::ImageSkia DesktopBackgroundController::GetWallpaper() const {
   if (current_wallpaper_)
-    return current_wallpaper_->wallpaper_image();
+    return current_wallpaper_->image();
   return gfx::ImageSkia();
 }
 
@@ -196,7 +197,7 @@ void DesktopBackgroundController::OnRootWindowAdded(
     return;
   gfx::Size max_display_size = GetMaxDisplaySizeInNative();
   // Handle resolution change for "built-in" images.
-  if (BACKGROUND_IMAGE == desktop_background_mode_ &&
+  if (desktop_background_mode_ == BACKGROUND_IMAGE &&
       current_wallpaper_.get() &&
       current_max_display_size_ != max_display_size) {
     current_max_display_size_ = max_display_size;
@@ -304,7 +305,9 @@ bool DesktopBackgroundController::MoveDesktopToUnlockedContainer() {
 
 void DesktopBackgroundController::OnDisplayConfigurationChanged() {
   gfx::Size max_display_size = GetMaxDisplaySizeInNative();
-  if (current_max_display_size_ != max_display_size) {
+  if (desktop_background_mode_ == BACKGROUND_IMAGE &&
+      current_wallpaper_.get() &&
+      current_max_display_size_ != max_display_size) {
     current_max_display_size_ = max_display_size;
     timer_.Stop();
     timer_.Start(FROM_HERE,
@@ -327,7 +330,8 @@ bool DesktopBackgroundController::DefaultWallpaperIsAlreadyLoadingOrLoaded(
 bool DesktopBackgroundController::CustomWallpaperIsAlreadyLoaded(
     const gfx::ImageSkia& image) const {
   return current_wallpaper_.get() &&
-      current_wallpaper_->wallpaper_image().BackedBySameObjectAs(image);
+      (WallpaperResizer::GetImageId(image) ==
+       current_wallpaper_->original_image_id());
 }
 
 void DesktopBackgroundController::SetDesktopBackgroundImageMode() {