cheets: implement cros side of WallpaperManagerService.

chrome/browser/chromeos/arc/arc_wallpaper_handler.cc

Index: chrome/browser/chromeos/arc/arc_wallpaper_handler.cc
diff --git a/chrome/browser/chromeos/arc/arc_wallpaper_handler.cc b/chrome/browser/chromeos/arc/arc_wallpaper_handler.cc
index 238a9837e121ffe019e3e1076c9429b7ff177420..83c2faab9d57f93a38a66a8174e7707d62f4e83f 100644
--- a/chrome/browser/chromeos/arc/arc_wallpaper_handler.cc
+++ b/chrome/browser/chromeos/arc/arc_wallpaper_handler.cc
@@ -4,10 +4,13 @@
 
 #include "chrome/browser/chromeos/arc/arc_wallpaper_handler.h"
 
+#include <cstdlib>

[hidehiko, 2016/08/22 02:30:10]

Clarification: for what?

 #include <string>
 #include <utility>
 #include <vector>
 
+#include "ash/desktop_background/desktop_background_controller.h"
+#include "ash/shell.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h"
@@ -16,7 +19,10 @@
 #include "components/wallpaper/wallpaper_files_id.h"
 #include "components/wallpaper/wallpaper_layout.h"
 #include "content/public/browser/browser_thread.h"
+#include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia.h"
+#include "ui/gfx/image/image_util.h"
+
 
 using user_manager::UserManager;
 
@@ -67,6 +73,11 @@ ArcWallpaperHandler::~ArcWallpaperHandler() {
   ImageDecoder::Cancel(this);
 }
 
+std::shared_ptr<ArcWallpaperHandler> ArcWallpaperHandler::Get() {
+  static std::shared_ptr<ArcWallpaperHandler> instance(new ArcWallpaperHandler);

[xiyuan, 2016/08/19 23:04:07]

We might want to use CR_DEFINE_STATIC_LOCAL or a LazyInstance instead of this.

[Luis Héctor Chávez, 2016/08/19 23:22:56]

DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

[hidehiko, 2016/08/22 02:30:10]

Could you get rid of Singleton?
Instead, ArcLauncher can keep the instance, and it can pass the ptr to necessary
services.

[Muyuan, 2016/08/22 22:25:00]

It sounds better :) thx.

+  return instance;
+}
+
 void ArcWallpaperHandler::SetWallpaper(std::vector<uint8_t> jpeg_data) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   // If there is an in-flight request, cancel it. It is safe to call Cancel()
@@ -76,6 +87,15 @@ void ArcWallpaperHandler::SetWallpaper(std::vector<uint8_t> jpeg_data) {
                                  ImageDecoder::ROBUST_JPEG_CODEC, true);
 }
 
+std::vector<uint8_t> ArcWallpaperHandler::GetWallpaper() const {

[Luis Héctor Chávez, 2016/08/19 23:22:56]

DCHECK_CURRENTLY_ON(...);

Note that we should not be encoding stuff on the UI thread.

[Muyuan, 2016/08/22 22:25:00]

Done.

+  ash::DesktopBackgroundController* dbc =
+      ash::Shell::GetInstance()->desktop_background_controller();
+  gfx::Image wallpaper(dbc->GetWallpaper());
+  std::vector<uint8_t> result;
+  gfx::JPEG1xEncodedDataFromImage(wallpaper, 100, &result);

[xiyuan, 2016/08/19 23:04:07]

What happens if there is no wallpaper and JPEG1xEncodedDataFromImage returns
false?

[Muyuan, 2016/08/22 22:25:00]

When there is no wallpaper, JPEG1xEncodedDataFromImage returns an empty vectory,
causing decoder in Android side to fail and WallpaperManager will handle it by
returning default Android wallpaper or null based on user's choice.

+  return std::move(result);

[Luis Héctor Chávez, 2016/08/19 23:22:56]

Can you run trybots? The compiler will complain about this pessimization and
will request you to omit the std::move when returning something.

[Muyuan, 2016/08/22 22:25:00]

Acknowledged.

+}
+
 void ArcWallpaperHandler::OnImageDecoded(const SkBitmap& bitmap) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   SetBitmapAsWallpaper(bitmap);