PlzNavigate: identify same-page browser-initiated navigation.

third_party/WebKit/public/platform/WebURLRequest.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 317 matching lines @@
   BLINK_PLATFORM_EXPORT void setInputPerfMetricReportPolicy(
       WebURLRequest::InputToLoadPerfMetricReportPolicy);
 
   // https://mikewest.github.io/cors-rfc1918/#external-request
   BLINK_PLATFORM_EXPORT bool isExternalRequest() const;
 
   BLINK_PLATFORM_EXPORT LoadingIPCType getLoadingIPCType() const;
 
   BLINK_PLATFORM_EXPORT void setNavigationStartTime(double);
 
+  // PlzNavigate: specify that the request was intended to be loaded as a same
+  // document navigation. No network requests should be made and the request
+  // should be dropped if the page's URL has changed in-between.

[nasko, 2017/01/23 19:10:13]

Would we drop the navigation if another same page navigation happened to be the
racy one? If not, then changing the URL means a different document, so let's be
more explicit. "if a different document was loaded in the frame in-between".

[arthursonzogni, 2017/01/24 15:17:05]

You are right. Done.

+  BLINK_PLATFORM_EXPORT void setIsSameDocumentNavigation(bool);
+
 #if INSIDE_BLINK
   BLINK_PLATFORM_EXPORT ResourceRequest& toMutableResourceRequest();
   BLINK_PLATFORM_EXPORT const ResourceRequest& toResourceRequest() const;
 
  protected:
   // Permit subclasses to set arbitrary ResourceRequest pointer as
   // |m_resourceRequest|. |m_ownedResourceRequest| is not set in this case.
   BLINK_PLATFORM_EXPORT explicit WebURLRequest(ResourceRequest&);
 #endif
 
  private:
   struct ResourceRequestContainer;
 
   // If this instance owns a ResourceRequest then |m_ownedResourceRequest|
   // is non-null and |m_resourceRequest| points to the ResourceRequest
   // instance it contains.
   std::unique_ptr<ResourceRequestContainer> m_ownedResourceRequest;
 
   // Should never be null.
   ResourceRequest* m_resourceRequest;
 };
 
 }  // namespace blink
 
 #endif