arc: IPC method to set custom wallpaper.

chrome/browser/chromeos/arc/arc_wallpaper_handler.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/arc_wallpaper_handler.h"
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/logging.h"
+#include "chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h"
+#include "chrome/browser/image_decoder.h"
+#include "components/signin/core/account_id/account_id.h"
+#include "components/user_manager/user_manager.h"
+#include "components/wallpaper/wallpaper_files_id.h"
+#include "components/wallpaper/wallpaper_layout.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace arc {
+
+namespace {
+
+constexpr char kAndroidWallpaperFilename[] = "android.jpg";
+
+// A thin wrapper of ImageDecoder to decode untrusted JPEG images.
+class UnsafeJpegImageDecoder : public ImageDecoder::ImageRequest {
+ public:
+  // Type of the callback function called on image decode completion.
+  // ImageSkia instance can be null value if decoding failed.
+  using Callback = base::Callback<void(const gfx::ImageSkia&)>;
+
+  // Starts decoding |jpeg_data| and invokes |callback| on completion.
+  static void Start(const std::string& jpeg_data, const Callback& callback);
+
+  // ImageDecoder::ImageRequest implementation.
+  void OnImageDecoded(const SkBitmap& image) override;
+  void OnDecodeImageFailed() override;
+
+ private:
+  UnsafeJpegImageDecoder(const std::string& jpeg_data,
+                         const Callback& callback);
+  ~UnsafeJpegImageDecoder() {}

[Yusuke Sato, 2016/06/15 19:44:32]

override = default;

[Shuhei Takahashi, 2016/06/15 22:58:38]

Done.

+
+  Callback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(UnsafeJpegImageDecoder);
+};
+
+void UnsafeJpegImageDecoder::Start(const std::string& jpeg_data,

[Yusuke Sato, 2016/06/15 19:44:32]

nit: What about adding '// static' here? I was a little bit confused about the
code and the comment.

[Shuhei Takahashi, 2016/06/15 22:58:38]

Done.

+                                   const Callback& callback) {
+  // Unfortunately ImageDecoder accepts a raw pointer to ImageRequest only,
+  // so callers must not delete ImageRequest instance until decoding finishes.
+  // In our case, let OnImageDecoded/OnDecodeImageFailed delete this
+  // instance on completion.
+  new UnsafeJpegImageDecoder(jpeg_data, callback);
+}
+
+void UnsafeJpegImageDecoder::OnImageDecoded(const SkBitmap& decoded_image) {
+  SkBitmap immutable(decoded_image);

[Yusuke Sato, 2016/06/15 19:44:32]

Can you add a short comment on why setImmutable() and MakeThreadSafe() is
necessary here? (sorry - I'm not very familiar with skia/image classes.)

[Shuhei Takahashi, 2016/06/15 22:58:38]

Hmm, actually I just followed the way
chrome/browser/chromeos/extensions/wallpaper_function_base.cc does, but forgot
to copy comments.

+  immutable.setImmutable();
+  gfx::ImageSkia final_image = gfx::ImageSkia::CreateFrom1xBitmap(immutable);
+  final_image.MakeThreadSafe();
+  callback_.Run(final_image);
+  delete this;
+}
+
+void UnsafeJpegImageDecoder::OnDecodeImageFailed() {
+  callback_.Run(gfx::ImageSkia());
+  delete this;
+}
+
+UnsafeJpegImageDecoder::UnsafeJpegImageDecoder(const std::string& jpeg_data,
+                                               const Callback& callback)
+    : callback_(callback) {
+  ImageDecoder::StartWithOptions(this, jpeg_data,
+                                 ImageDecoder::ROBUST_JPEG_CODEC, true);
+}
+
+// Sets a decoded image as the wallpaper.
+void SetImageAsWallpaper(const gfx::ImageSkia& image) {
+  if (image.isNull()) {

[Yusuke Sato, 2016/06/15 19:44:32]

Does this catch the callback_.Run(gfx::ImageSkia()); case at line 69? Just
wanted to make sure.

[Shuhei Takahashi, 2016/06/15 22:58:38]

Yes.

https://cs.chromium.org/chromium/src/ui/gfx/image/image_skia.cc?sq=package:ch...

  ImageSkia::ImageSkia() : storage_(NULL) {

https://cs.chromium.org/chromium/src/ui/gfx/image/image_skia.h?dr=CSs&q=image...

  bool isNull() const { return storage_.get() == NULL; }

+    LOG(ERROR) << "Failed to decode wallpaper image.";
+    return;
+  }
+
+  chromeos::WallpaperManager* wallpaper_manager =
+      chromeos::WallpaperManager::Get();
+
+  const AccountId& account_id =
+      user_manager::UserManager::Get()->GetPrimaryUser()->GetAccountId();
+  wallpaper::WallpaperFilesId wallpaper_files_id =
+      wallpaper_manager->GetFilesId(account_id);
+  bool update_wallpaper =
+      account_id ==
+      user_manager::UserManager::Get()->GetActiveUser()->GetAccountId();
+  // TODO(crbug.com/618922): Allow specifying layout.
+  wallpaper_manager->SetCustomWallpaper(
+      account_id, wallpaper_files_id, kAndroidWallpaperFilename,
+      wallpaper::WALLPAPER_LAYOUT_STRETCH, user_manager::User::CUSTOMIZED,
+      image, update_wallpaper);
+
+  // TODO(crbug.com/618922): Register the wallpaper to Chrome OS wallpaper
+  // picker. Currently the new wallpaper does not appear there. The best way to
+  // make this happen seems to do the same things as wallpaper_api.cc and
+  // wallpaper_private_api.cc.
+}
+
+}  // namespace
+
+void ArcWallpaperHandler::SetWallpaper(const std::string& jpeg_data) {
+  UnsafeJpegImageDecoder::Start(jpeg_data, base::Bind(&SetImageAsWallpaper));
+}
+
+}  // namespace arc