Implicitly copy only head and form body for main resource loading.

This CL is refactoring.
This CL extracts ResourceRequest::CopyFrom() in main resource loading
path that fetch doesn't use.
This is a preparation for fetch upload streaming.

Bug: 787704
Change-Id: I0b53eca0dac33d1aeffd81ddb39d8c49b9f70824
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2076823Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745361}

third_party/blink/renderer/core/loader/frame_load_request.cc

@@ -45,7 +45,8 @@ FrameLoadRequest::FrameLoadRequest(Document* origin_document,
                                    const ResourceRequest& resource_request)
     : origin_document_(origin_document),
       should_send_referrer_(kMaybeSendReferrer) {
-  resource_request_.CopyFrom(resource_request);
+  resource_request_.CopyHeadFrom(&resource_request);
+  resource_request_.SetHttpBody(resource_request.HttpBody());
   resource_request_.SetMode(network::mojom::RequestMode::kNavigate);
   resource_request_.SetCredentialsMode(
       network::mojom::CredentialsMode::kInclude);

third_party/blink/renderer/platform/exported/web_url_request.cc

@@ -117,7 +117,8 @@ void WebURLRequest::CopyFrom(const WebURLRequest& r) {
   DCHECK_EQ(owned_resource_request_.get(), resource_request_);
   DCHECK(owned_resource_request_->IsNull());
   DCHECK(this != &r);
-  resource_request_->CopyFrom(*r.resource_request_);
+  resource_request_->CopyHeadFrom(r.resource_request_);
+  resource_request_->SetHttpBody(r.resource_request_->HttpBody());
 }
 
 bool WebURLRequest::IsNull() const {

third_party/blink/renderer/platform/loader/fetch/resource_request.cc

@@ -113,6 +113,10 @@ void ResourceRequest::CopyFrom(const ResourceRequest& src) {
   *this = src;
 }
 
+void ResourceRequest::CopyHeadFrom(const ResourceRequestHead* src) {
+  this->ResourceRequestHead::operator=(*src);
+}
+
 std::unique_ptr<ResourceRequest> ResourceRequest::CreateRedirectRequest(
     const KURL& new_url,
     const AtomicString& new_method,

third_party/blink/renderer/platform/loader/fetch/resource_request.h

@@ -557,6 +557,7 @@ class PLATFORM_EXPORT ResourceRequest final : public ResourceRequestHead {
   // TODO(yoichio): Use move semantics as much as possible.
   // See crbug.com/787704.
   void CopyFrom(const ResourceRequest&);
+  void CopyHeadFrom(const ResourceRequestHead*);
 
   // Constructs a new ResourceRequest for a redirect from this instance.
   std::unique_ptr<ResourceRequest> CreateRedirectRequest(