Use mojo for Chrome Loading, Part 1

content/browser/loader/url_loader_factory_impl.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 "content/browser/loader/url_loader_factory_impl.h"
+
+#include <memory>
+
+#include "base/memory/ptr_util.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
+#include "content/browser/loader/resource_message_filter.h"
+#include "content/common/resource_messages.h"
+#include "content/common/resource_request.h"
+#include "content/common/url_loader.mojom.h"
+
+namespace content {
+
+namespace {
+
+// This class is an implementation of mojom::URLLoader which is a resource
+// loader interface with Mojo.
+class URLLoaderImpl final : public mojom::URLLoader {

[mmenke, 2016/05/26 21:46:09]

I don't suppose there's some mojo signal if the other process is killed?  Just
wondering if we can work our way towards no longer having to have the RDH care
about all that stuff (Have it not care about RenderView tear down, too, for that
matter.

binding_.set_connection_error_handler?

[yhirano, 2016/05/27 11:30:34]

Can you tell me if process death is the only cause of
CancelRequestsForRoute(child_id, MSG_ROUTING_NONE)?

If that's true, we can move unstarted_laoder_ from ResourceDispatcherHostImpl to
URLLoaderImpl('s static member) by using set_connection_error_handler. 

[mmenke, 2016/05/27 15:39:26]

CancelRequestsForProcess is only called on process deletion. 
CancelRequestsForRoute is called whenever a RenderFrame goes away.  Suppose we
may get races if we delay these to wait on mojo calls - seems like this would
require more investigation.

+ public:
+  // Creates a URLLoader. This function returns nothing and registers the
+  // created instance to the ResourceDispatcherHostImpl instead.
+  static void Create(scoped_refptr<ResourceMessageFilter> filter,
+                     mojom::URLLoaderRequest request) {
+    int child_id = filter->child_id();
+    ResourceDispatcherHostImpl::Get()->AddUnstartedURLLoader(
+        child_id,
+        base::WrapUnique(new URLLoaderImpl(filter.get(), std::move(request))));
+  }
+
+  ~URLLoaderImpl() override {}
+
+  void Start(int32_t request_id,
+             const ResourceRequest& request,
+             mojom::URLLoaderClientPtr client) override {
+    DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+    ResourceMessageFilter* filter = resource_message_filter_.get();
+    if (!filter) {
+      // TODO(yhirano): Cancel the request.
+      return;
+    }
+
+    std::unique_ptr<mojom::URLLoader> that =
+        ResourceDispatcherHostImpl::Get()->TakeUnstartedURLLoader(this);
+    DCHECK(that);
+
+    // TODO(yhirano): Provide the right routing ID.
+    const int routing_id = 0;
+    ResourceDispatcherHostImpl* rdh = ResourceDispatcherHostImpl::Get();
+    rdh->OnRequestResourceWithMojo(routing_id, request_id, request,
+                                   std::move(that), std::move(client), filter);
+  }
+  void FollowRedirect() override {}
+  void Cancel() override {}
+
+ private:
+  URLLoaderImpl(ResourceMessageFilter* filter,
+                mojo::InterfaceRequest<mojom::URLLoader> request)
+      : resource_message_filter_(filter->GetWeakPtr()),
+        binding_(this, std::move(request)) {}
+
+  base::WeakPtr<ResourceMessageFilter> resource_message_filter_;
+  mojo::Binding<mojom::URLLoader> binding_;
+};
+
+}  // namespace
+
+URLLoaderFactoryImpl::URLLoaderFactoryImpl(
+    scoped_refptr<ResourceMessageFilter> resource_message_filter,
+    mojo::InterfaceRequest<mojom::URLLoaderFactory> request)
+    : resource_message_filter_(resource_message_filter),
+      binding_(this, std::move(request)) {}

[mmenke, 2016/05/26 21:46:09]

DCHECK_CURRENTLY_ON(BrowserThread::UI);?

[yhirano, 2016/05/27 11:30:34]

Done.

+
+URLLoaderFactoryImpl::~URLLoaderFactoryImpl() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);

[mmenke, 2016/05/26 21:46:09]

include browser_thread.h

[yhirano, 2016/05/27 11:30:34]

Done.

+}
+
+void URLLoaderFactoryImpl::CreateURLLoader(mojom::URLLoaderRequest request) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&URLLoaderImpl::Create, resource_message_filter_,
+                 base::Passed(std::move(request))));

[mmenke, 2016/05/26 21:46:09]

include base/bind.h

[yhirano, 2016/05/27 11:30:34]

Done.

+}
+
+}  // namespace content