[fetch] Refactor RawResource functions to avoid copy.

This patch makes some parameters |const T&| than |T| to avoid
unnecessary copy.

Bug: 787704
Change-Id: I914043a82192c18a3db535c77a3a29ab742fd1f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1989319Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729650}

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

@@ -173,8 +173,8 @@ void RawResource::DidAddClient(ResourceClient* c) {
   RevalidationStartForbiddenScope revalidation_start_forbidden_scope(this);
   RawResourceClient* client = static_cast<RawResourceClient*>(c);
   for (const auto& redirect : RedirectChain()) {
-    ResourceRequest request(redirect.request_);
-    client->RedirectReceived(this, request, redirect.redirect_response_);
+    client->RedirectReceived(this, redirect.request_,
+                             redirect.redirect_response_);
     if (!HasClient(c))
       return;
   }

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

@@ -63,7 +63,7 @@ class PLATFORM_EXPORT RawResource final : public Resource {
                                     RawResourceClient*);
 
   // Exposed for testing
-  static RawResource* CreateForTest(ResourceRequest request,
+  static RawResource* CreateForTest(const ResourceRequest& request,
                                     ResourceType type) {
     ResourceLoaderOptions options;
     return MakeGarbageCollected<RawResource>(request, type, options);