PlzNavigate: Add first version of NavigationURLLoader.

content/browser/loader/navigation_url_loader_core.cc

+// Copyright 2014 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/navigation_url_loader_core.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "content/browser/frame_host/navigation_request_info.h"
+#include "content/browser/loader/navigation_resource_handler.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
+#include "content/common/navigation_params.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/stream_handle.h"
+#include "content/public/common/resource_response.h"
+#include "net/base/net_errors.h"
+#include "net/url_request/redirect_info.h"
+
+namespace content {
+
+NavigationURLLoaderCore::NavigationURLLoaderCore(
+    const base::WeakPtr<NavigationURLLoaderImpl>& loader)
+    : loader_(loader),
+      resource_handler_(nullptr) {
+}
+
+NavigationURLLoaderCore::~NavigationURLLoaderCore() {
+  if (resource_handler_) {
+    resource_handler_->Cancel();

[mmenke, 2014/10/22 15:32:58]

Not a real issue, but just for my edification...This does not result in calling
into NavigationURLLoaderCore::NotifyRequestFailed, because URLRequest passes the
cancellation message back to the ResourceLoader asynchronously, by which point
this has been deleted, anyways.  Not that NotifyRequestFailed would be a
problem, anyways, due to the whole WeakPtr thing.

[davidben, 2014/10/22 20:58:04]

Well, there isn't a WeakPtr on this end. The Cancel hook is how the resource
handler knows the Core has gone away. It NULLs core_ at the end of Cancel.

+    resource_handler_ = nullptr;

[mmenke, 2014/10/22 15:32:58]

NULLing out resource_handler_ doesn't seem to get us anything.

[davidben, 2014/10/22 20:58:04]

Done.

+  }
+}
+
+void NavigationURLLoaderCore::Start(
+    ResourceContext* resource_context,
+    int64 frame_tree_node_id,
+    const CommonNavigationParams& common_params,
+    scoped_ptr<NavigationRequestInfo> request_info,
+    ResourceRequestBody* request_body) {
+  ResourceDispatcherHostImpl::Get()->BeginNavigationRequest(
+      resource_context, frame_tree_node_id,
+      common_params, *request_info, request_body,
+      this);
+}
+
+void NavigationURLLoaderCore::FollowRedirect() {
+  if (resource_handler_)
+    resource_handler_->FollowRedirect();
+}
+
+
+void NavigationURLLoaderCore::NotifyRequestRedirected(
+    const net::RedirectInfo& redirect_info,
+    ResourceResponse* response) {
+  // Make a copy of the ResourceResponse before it is passed to another thread.
+  //
+  // TODO(davidben): This copy could be avoided if ResourceResponse weren't
+  // reference counted and the loader stack passed unique ownership of the
+  // response. https://crbug.com/416050
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&NavigationURLLoaderImpl::NotifyRequestRedirected, loader_,
+                 redirect_info, response->DeepCopy()));
+}
+
+void NavigationURLLoaderCore::NotifyResponseStarted(
+    ResourceResponse* response,
+    scoped_ptr<StreamHandle> body) {
+  // If, by the time the task reaches the UI thread, |loader_| has already been
+  // destroyed, NotifyResponseStarted will not run. |body| will be destructed
+  // and the request released at that point.
+
+  // Make a copy of the ResourceResponse before it is passed to another thread.
+  //
+  // TODO(davidben): This copy could be avoided if ResourceResponse weren't
+  // reference counted and the loader stack passed unique ownership of the
+  // response. https://crbug.com/416050
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&NavigationURLLoaderImpl::NotifyResponseStarted, loader_,
+                 response->DeepCopy(), base::Passed(&body)));
+}
+
+void NavigationURLLoaderCore::NotifyRequestFailed(int net_error) {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&NavigationURLLoaderImpl::NotifyRequestFailed, loader_,
+                 net_error));
+}
+
+}  // namespace content