reduce setting wallpaper latency.

chrome/browser/chromeos/arc/wallpaper/arc_wallpaper_service.cc

 // Copyright 2016 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 "chrome/browser/chromeos/arc/wallpaper/arc_wallpaper_service.h"
 
 #include "ash/common/wallpaper/wallpaper_controller.h"
 #include "ash/common/wm_shell.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 89 matching lines @@
   ash::WmShell::Get()->wallpaper_controller()->AddObserver(this);
 }
 
 void ArcWallpaperService::OnInstanceClosed() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   ash::WallpaperController* wc = GetWallpaperController();
   if (wc)
     wc->RemoveObserver(this);
 }
 
-void ArcWallpaperService::SetWallpaper(const std::vector<uint8_t>& png_data) {
+void ArcWallpaperService::SetWallpaper(const std::vector<uint8_t>& data) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   ImageDecoder::Cancel(this);
-  ImageDecoder::StartWithOptions(this, png_data, ImageDecoder::ROBUST_PNG_CODEC,
-                                 true);
+  ImageDecoder::StartWithOptions(this, data, ImageDecoder::DEFAULT_CODEC, true);
 }
 
 void ArcWallpaperService::GetWallpaper(const GetWallpaperCallback& callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   ash::WallpaperController* wc = ash::WmShell::Get()->wallpaper_controller();
   gfx::ImageSkia wallpaper = wc->GetWallpaper();
   base::PostTaskAndReplyWithResult(
       content::BrowserThread::GetBlockingPool(), FROM_HERE,
       base::Bind(&EncodeImagePng, wallpaper), callback);
 }
@@ skipping 12 matching lines @@
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   auto* wallpaper_instance =
       arc_bridge_service()->wallpaper()->GetInstanceForMethod(
           "OnWallpaperChanged", kMinOnWallpaperChangedVersion);
   if (!wallpaper_instance)
     return;
   wallpaper_instance->OnWallpaperChanged();
 }
 
 }  // namespace arc