Fetch ARC Kiosk app name and icon from Android side.

chrome/browser/chromeos/app_mode/kiosk_app_icon_loader.cc

+// Copyright 2017 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/app_mode/kiosk_app_icon_loader.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/files/file_util.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/public/browser/browser_thread.h"
+
+using content::BrowserThread;
+
+namespace chromeos {
+
+KioskAppIconLoader::IconImageRequest::IconImageRequest(
+    const scoped_refptr<base::SequencedTaskRunner>& task_runner,
+    KioskAppIconLoader* icon_loader)
+    : ImageRequest(task_runner), icon_loader_(icon_loader) {}
+
+void KioskAppIconLoader::IconImageRequest::OnImageDecoded(
+    const SkBitmap& decoded_image) {
+  icon_loader_->icon_ = gfx::ImageSkia::CreateFrom1xBitmap(decoded_image);
+  icon_loader_->icon_.MakeThreadSafe();
+  icon_loader_->ReportResultOnBlockingPool(SUCCESS);
+  delete this;
+}
+
+void KioskAppIconLoader::IconImageRequest::OnDecodeImageFailed() {
+  icon_loader_->ReportResultOnBlockingPool(FAILED_TO_DECODE);
+  delete this;
+}
+
+KioskAppIconLoader::KioskAppIconLoader(const base::WeakPtr<Delegate>& client,
+                                       const base::FilePath& icon_path)
+    : client_(client), icon_path_(icon_path), load_result_(SUCCESS) {}
+
+KioskAppIconLoader::~KioskAppIconLoader() = default;
+
+void KioskAppIconLoader::Start() {
+  base::SequencedWorkerPool* pool = BrowserThread::GetBlockingPool();
+  base::SequencedWorkerPool::SequenceToken token = pool->GetSequenceToken();
+  task_runner_ = pool->GetSequencedTaskRunnerWithShutdownBehavior(
+      token, base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+  task_runner_->PostTask(FROM_HERE,
+                         base::Bind(&KioskAppIconLoader::LoadOnBlockingPool,
+                                    base::Unretained(this)));

[khmel, 2017/03/27 22:56:34]

We might need weak pointer binding instead of Unretained or add comment why it
is safe.

[Sergey Poromov, 2017/03/28 15:25:55]

I just refactored to extract this class from KioskAppData, not going to change
any internal behavior.
I suspect that here in below it was written this way because the class is
self-owned and deleted after NotifyClient().

+xiyuan@ for more comments as he implemented the class 4 years ago:
http://crrev.com/12223018

[xiyuan, 2017/03/28 16:50:09]

The reading is correct.

IconLoader manages its own lifetime and no one keeps a reference to it. The
class must be created then followed by a Start(). There is no way to cancel the
load request after Start(). Its |client_| is a WeakPtr and can go away before
the loader. But loader has to finish the full cycle until NotifyClient is
called.

Adding a comment to explain would be good to make code easier to read.

+}
+
+void KioskAppIconLoader::LoadOnBlockingPool() {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+
+  std::string data;
+  if (!base::ReadFileToString(base::FilePath(icon_path_), &data)) {
+    ReportResultOnBlockingPool(FAILED_TO_LOAD);
+    return;
+  }
+  raw_icon_ = base::RefCountedString::TakeString(&data);
+
+  IconImageRequest* image_request = new IconImageRequest(task_runner_, this);
+  ImageDecoder::Start(image_request, raw_icon_->data());
+}
+
+void KioskAppIconLoader::ReportResultOnBlockingPool(LoadResult result) {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+
+  load_result_ = result;
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&KioskAppIconLoader::ReportResultOnUIThread,
+                 base::Unretained(this)));

[khmel, 2017/03/27 22:56:33]

Use weak pointer instead of Unretained?

+}
+
+void KioskAppIconLoader::NotifyClient() {
+  if (!client_)
+    return;
+
+  if (load_result_ == SUCCESS)

[khmel, 2017/03/27 22:56:32]

You set and read load_results_ from different threads IIUC

+    client_->OnIconLoadSuccess(icon_);
+  else
+    client_->OnIconLoadFailure();
+}
+
+void KioskAppIconLoader::ReportResultOnUIThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  NotifyClient();
+  delete this;
+}
+
+}  // namespace chromeos