Merge ThreadableLoaderClient's redirect callbacks

Two behavior changes:
* Previously, DidReceiveRedirectTo() was called for almost all
  redirects (barring a few early-exits), but WillFollowRedirect()
  was only called for same-origin redirects. Now the single callback,
  WillFollowRedirect(), is called whenever DidReceiveRedirectTo()
  used to be called.
* Previously, due to a bug in
  https://chromium-review.googlesource.com/c/chromium/src/+/1147890,
  the return value of WillFollowRedirect() was ignored when
  out-of-blink CORS was enabled. That return value is now honored.

Change-Id: I9c1ebb30b23aea77114711e0ee1b5dd0409c7166
Reviewed-on: https://chromium-review.googlesource.com/1150695
Commit-Queue: Nate Chapin <japhet@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579253}

third_party/blink/renderer/core/exported/web_associated_url_loader_impl_test.cc

@@ -520,7 +520,7 @@ TEST_F(WebAssociatedURLLoaderTest,
 
   ServeRequests();
   // We should get a notification about access control check failure.
-  EXPECT_FALSE(will_follow_redirect_);
+  EXPECT_TRUE(will_follow_redirect_);
   EXPECT_FALSE(did_receive_response_);
   EXPECT_FALSE(did_receive_data_);
   EXPECT_TRUE(did_fail_);
@@ -568,8 +568,7 @@ TEST_F(WebAssociatedURLLoaderTest,
   EXPECT_TRUE(expected_loader_);
   expected_loader_->LoadAsynchronously(request, this);
   ServeRequests();
-  // We should not receive a notification for the redirect.
-  EXPECT_FALSE(will_follow_redirect_);
+  EXPECT_TRUE(will_follow_redirect_);
   EXPECT_TRUE(did_receive_response_);
   EXPECT_TRUE(did_receive_data_);
   EXPECT_TRUE(did_finish_loading_);

third_party/blink/renderer/core/fetch/fetch_manager.cc

@@ -179,7 +179,7 @@ class FetchManager::Loader final
   ~Loader() override;
   virtual void Trace(blink::Visitor*);
 
-  void DidReceiveRedirectTo(const KURL&) override;
+  bool WillFollowRedirect(const KURL&, const ResourceResponse&) override;
   void DidReceiveResponse(unsigned long,
                           const ResourceResponse&,
                           std::unique_ptr<WebDataConsumerHandle>) override;
@@ -376,8 +376,10 @@ void FetchManager::Loader::Trace(blink::Visitor* visitor) {
   visitor->Trace(execution_context_);
 }
 
-void FetchManager::Loader::DidReceiveRedirectTo(const KURL& url) {
+bool FetchManager::Loader::WillFollowRedirect(const KURL& url,
+                                              const ResourceResponse&) {
   url_list_.push_back(url);
+  return true;
 }
 
 void FetchManager::Loader::DidReceiveResponse(

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

@@ -671,16 +671,10 @@ bool ThreadableLoader::RedirectReceived(
       return false;
     }
 
-    if (out_of_blink_cors_) {
-      client_->DidReceiveRedirectTo(new_url);
-      client_->WillFollowRedirect(new_url, redirect_response);
-      return true;
-    }
-
     // Allow same origin requests to continue after allowing clients to audit
     // the redirect.
-    if (IsAllowedRedirect(new_request.GetFetchRequestMode(), new_url)) {
-      client_->DidReceiveRedirectTo(new_url);
+    if (out_of_blink_cors_ ||
+        IsAllowedRedirect(new_request.GetFetchRequestMode(), new_url)) {
       return client_->WillFollowRedirect(new_url, redirect_response);
     }
 
@@ -721,7 +715,7 @@ bool ThreadableLoader::RedirectReceived(
       }
     }
 
-    client_->DidReceiveRedirectTo(new_url);
+    client_->WillFollowRedirect(new_url, redirect_response);
 
     // FIXME: consider combining this with CORS redirect handling performed by
     // CrossOriginAccessControl::handleRedirect().

third_party/blink/renderer/core/loader/threadable_loader_client.h

@@ -50,8 +50,6 @@ class CORE_EXPORT ThreadableLoaderClient {
  public:
   virtual void DidSendData(unsigned long long /*bytesSent*/,
                            unsigned long long /*totalBytesToBeSent*/) {}
-  // TODO(japhet?): Merge these redirect callbacks.
-  virtual void DidReceiveRedirectTo(const KURL&) {}
   virtual bool WillFollowRedirect(const KURL& new_url,
                                   const ResourceResponse&) {
     return true;