[Payments] Implement payment instrument icons

content/browser/payments/payment_instrument_icon_fetcher.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 "content/browser/payments/payment_instrument_icon_fetcher.h"
+
+#include "base/base64.h"
+#include "base/bind_helpers.h"
+#include "content/browser/storage_partition_impl.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/common/service_manager_connection.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_status_code.h"
+#include "net/traffic_annotation/network_traffic_annotation.h"
+#include "services/data_decoder/public/cpp/decode_image.h"
+#include "services/service_manager/public/cpp/connector.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gfx/image/image.h"
+
+namespace content {
+
+namespace {
+
+net::NetworkTrafficAnnotationTag g_traffic_annotation =
+    net::DefineNetworkTrafficAnnotation("payment_instrument_icon_fetcher", R"(
+        semantics {
+          sender: "Web Payments"
+          description:
+            "Chromium downloads payment instrument icons when registering
+             payment instruments."
+          trigger:
+            "When user navigates to a website to register web payment apps."
+          data:
+            "URL of the required icon to fetch. No user information is sent."
+          destination: WEBSITE
+        }
+        policy {
+          cookies_allowed: false
+          setting:
+            "This feature cannot be disabled in settings. Users can refuse
+             to install web payment apps."
+          policy_exception_justification: "Not implemented."
+        })");
+
+}  // namespace
+
+PaymentInstrumentIconFetcher::PaymentInstrumentIconFetcher()
+    : checking_image_object_index_(0) {}
+PaymentInstrumentIconFetcher::~PaymentInstrumentIconFetcher() {}
+
+void PaymentInstrumentIconFetcher::Start(
+    const std::vector<payments::mojom::ImageObjectPtr>& image_objects,
+    scoped_refptr<ServiceWorkerContextWrapper> service_worker_context,
+    PaymentInstrumentIconFetcherCallback callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  for (const auto& obj : image_objects) {
+    payments::mojom::ImageObjectPtr image_object =
+        payments::mojom::ImageObject::New();
+    image_object->src = obj->src;
+    image_objects_.emplace_back(std::move(image_object));

[dcheng, 2017/06/10 00:37:10]

Can this take |image_objects| by value, so we can just std::move() it?

[gogerald1, 2017/06/12 16:19:43]

Done.

+  }
+  DCHECK_GT(image_objects_.size(), 0U);
+
+  callback_ = std::move(callback);
+
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&PaymentInstrumentIconFetcher::StartFromUIThread,

[dcheng, 2017/06/10 00:37:10]

Nit: might be nice to use base::BindOnce here, since this will only be called
once.

[gogerald1, 2017/06/12 16:19:44]

Done.

+                 base::Unretained(this), service_worker_context));

[dcheng, 2017/06/10 00:37:10]

Please document why Unretained is safe here.

[dcheng, 2017/06/10 00:37:10]

Also, please use std::move(service_worker_context) since we're passing
|service_worker_context| by value here.

[gogerald1, 2017/06/12 16:19:43]

Done.

[gogerald1, 2017/06/12 16:19:44]

Done.

+}
+
+void PaymentInstrumentIconFetcher::StartFromUIThread(
+    scoped_refptr<ServiceWorkerContextWrapper> service_worker_context) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  url_request_context_getter_ = scoped_refptr<net::URLRequestContextGetter>(

[dcheng, 2017/06/10 00:37:10]

It's pretty unusual to see this written out explicitly. I would suggest using:
url_request_context_getter_.reset(
    service_worker_context->storage_partition()->GetURLRequestContext());

[gogerald1, 2017/06/12 16:19:43]

Done. scoped_refptr has no reset method, but I've simplified the expression.

+      service_worker_context->storage_partition()->GetURLRequestContext());
+  if (url_request_context_getter_.get() == nullptr) {

[dcheng, 2017/06/10 00:37:10]

Nit: just if (url_request_context_getter_) here

[gogerald1, 2017/06/12 16:19:43]

Done.

+    PostCallbackToIOThread("");
+    return;
+  }
+
+  FetchIcon();
+}
+
+void PaymentInstrumentIconFetcher::FetchIcon() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  if (checking_image_object_index_ >= image_objects_.size()) {
+    PostCallbackToIOThread("");
+    return;
+  }
+
+  GURL* icon_src_url = &(image_objects_[checking_image_object_index_]->src);
+  if (!icon_src_url->is_valid()) {
+    checking_image_object_index_++;
+    FetchIcon();
+    return;
+  }
+
+  fetcher_ = net::URLFetcher::Create(*icon_src_url, net::URLFetcher::GET, this,
+                                     g_traffic_annotation);
+  fetcher_->SetRequestContext(url_request_context_getter_.get());
+  fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                         net::LOAD_DO_NOT_SAVE_COOKIES);
+  fetcher_->SetStopOnRedirect(true);
+  fetcher_->Start();
+}
+
+void PaymentInstrumentIconFetcher::OnURLFetchComplete(
+    const net::URLFetcher* source) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  DCHECK_EQ(fetcher_.get(), source);
+  std::unique_ptr<net::URLFetcher> free_fetcher = std::move(fetcher_);
+
+  std::string data;
+  if (!(source->GetStatus().is_success() &&
+        source->GetResponseCode() == net::HTTP_OK &&
+        source->GetResponseAsString(&data))) {
+    checking_image_object_index_++;
+    FetchIcon();
+    return;
+  }
+
+  service_manager::mojom::ConnectorRequest connector_request;
+  std::unique_ptr<service_manager::Connector> connector =
+      service_manager::Connector::Create(&connector_request);
+  content::ServiceManagerConnection::GetForProcess()
+      ->GetConnector()
+      ->BindConnectorRequest(std::move(connector_request));
+
+  std::vector<uint8_t> image_data(data.begin(), data.end());
+  data_decoder::DecodeImage(
+      connector.get(), image_data, data_decoder::mojom::ImageCodec::DEFAULT,
+      false, data_decoder::kDefaultMaxSizeInBytes, gfx::Size(),
+      base::Bind(&PaymentInstrumentIconFetcher::DecodeImageCallback,
+                 base::Unretained(this)));
+}
+
+void PaymentInstrumentIconFetcher::DecodeImageCallback(const SkBitmap& bitmap) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  if (bitmap.isNull() || bitmap.empty()) {

[dcheng, 2017/06/10 00:37:10]

Use bitmap.drawsNothing(), which does both of these checks.

[gogerald1, 2017/06/12 16:19:43]

Done.

+    checking_image_object_index_++;
+    FetchIcon();
+    return;
+  }
+
+  gfx::Image decoded_image = gfx::Image::CreateFrom1xBitmap(bitmap);
+  scoped_refptr<base::RefCountedMemory> raw_data = decoded_image.As1xPNGBytes();
+  std::string base_64;
+  base::Base64Encode(
+      base::StringPiece(raw_data->front_as<char>(), raw_data->size()),
+      &base_64);
+
+  PostCallbackToIOThread(base_64);
+}
+
+void PaymentInstrumentIconFetcher::PostCallbackToIOThread(
+    const std::string& decoded_data) {
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::BindOnce(std::move(callback_), decoded_data));
+}
+
+}  // namespace content