Add PDF compositor service

components/printing/service/pdf_compositor_service.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 "components/printing/service/pdf_compositor_service.h"
+
+#include <utility>
+
+#include "base/lazy_instance.h"
+#include "base/memory/discardable_memory.h"
+#include "base/memory/ptr_util.h"
+#include "components/printing/service/pdf_compositor_impl.h"
+#include "components/printing/service/public/interfaces/pdf_compositor.mojom.h"
+#include "content/public/common/service_names.mojom.h"
+#include "content/public/utility/utility_thread.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "services/service_manager/public/cpp/connector.h"
+#include "services/service_manager/public/cpp/service_context.h"
+
+namespace {
+
+base::LazyInstance<std::string>::Leaky g_creator;

[dcheng, 2017/05/10 07:36:48]

It feels a bit awkward to hold this as a LazyInstance. Won't subsequent calls to
PdfCompositorService::Create() change this and cause requests for future
PdfCompositors to be created with a different creator?

[Wei Li, 2017/05/11 16:53:02]

I have not found a better solution. This string should be constant for a give
product since it stores user agent.
User agent is composed after browser starts. So passing in when creating the
service seems the right moment.

[dcheng, 2017/05/12 08:14:20]

How about just having a static function to configure this, and have
PdfCompositor just use the static directly? If it's stored as a member on each
PdfCompositorService/PdfCompositor, it kind of looks like it can be different
for different PdfCompositors -- but from this comment, it seems like it's
actually constant.

+
+void OnPdfCompositorRequest(
+    service_manager::ServiceContextRefFactory* ref_factory,
+    const service_manager::BindSourceInfo& source_info,
+    printing::mojom::PdfCompositorRequest request) {
+  mojo::MakeStrongBinding(base::MakeUnique<printing::PdfCompositorImpl>(
+                              g_creator.Get(), ref_factory->CreateRef()),
+                          std::move(request));
+}
+}  // namespace
+
+namespace printing {
+
+PdfCompositorService::PdfCompositorService() : weak_factory_(this) {}
+
+PdfCompositorService::~PdfCompositorService() = default;
+
+// static
+std::unique_ptr<service_manager::Service> PdfCompositorService::Create(
+    const std::string& creator) {
+  g_creator.Get() = creator;
+  return base::MakeUnique<printing::PdfCompositorService>();
+}
+
+void PdfCompositorService::OnStart() {
+  // Set up discardable memory manager.
+  discardable_memory::mojom::DiscardableSharedMemoryManagerPtr manager_ptr;
+  context()->connector()->BindInterface(content::mojom::kBrowserServiceName,
+                                        &manager_ptr);
+  discardable_shared_memory_manager_ = base::MakeUnique<
+      discardable_memory::ClientDiscardableSharedMemoryManager>(
+      std::move(manager_ptr), content::UtilityThread::Get()->GetIOTaskRunner());
+  DCHECK(discardable_shared_memory_manager_);
+  base::DiscardableMemoryAllocator::SetInstance(
+      discardable_shared_memory_manager_.get());
+
+  ref_factory_ = base::MakeUnique<service_manager::ServiceContextRefFactory>(
+      base::Bind(&service_manager::ServiceContext::RequestQuit,
+                 base::Unretained(context())));
+  registry_.AddInterface(
+      base::Bind(&OnPdfCompositorRequest, ref_factory_.get()));
+}
+
+void PdfCompositorService::OnBindInterface(
+    const service_manager::BindSourceInfo& source_info,
+    const std::string& interface_name,
+    mojo::ScopedMessagePipeHandle interface_pipe) {
+  registry_.BindInterface(source_info, interface_name,
+                          std::move(interface_pipe));
+}
+
+}  // namespace printing