Solidify Entry discarding logic (NavigationHandle keeps its ID)

content/browser/frame_host/navigation_handle_impl.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 
 #include "content/public/browser/navigation_handle.h"
 
 #include <stddef.h>
@@ skipping 48 matching lines @@
 //
 // When PlzNavigate is enabled, the NavigationHandleImpl will never be reset
 // following the receipt of a DidStartProvisionalLoad IPC. There are also no
 // transferring navigations. The other causes of NavigationHandleImpl reset in
 // the RenderFrameHost still apply.
 class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
  public:
   // |navigation_start| comes from the DidStartProvisionalLoad IPC, which tracks
   // both renderer-initiated and browser-initiated navigation start.
   // PlzNavigate: This value always comes from the CommonNavigationParams
   // associated with this navigation.

[Charlie Reis, 2016/02/05 19:36:11]

Need to document what cases it's ok for the NavEntry to be null.  Am I right
that it is only null for synchronous navigations, when there is no pending
NavEntry?

[Charlie Harrison, 2016/02/05 23:10:23]

Yeah, that what I gathered. Perhaps the nav_entry_id should be renamed to
pending_nav_entry_id? The navigation handle goes away after commit, after all.

[Charlie Reis, 2016/02/06 00:54:57]

Yes, I like pending_nav_entry_id.

   static scoped_ptr<NavigationHandleImpl> Create(
       const GURL& url,
       FrameTreeNode* frame_tree_node,
-      const base::TimeTicks& navigation_start);
+      const base::TimeTicks& navigation_start,
+      NavigationEntry* navigation_entry);
   ~NavigationHandleImpl() override;
 
   // NavigationHandle implementation:
   const GURL& GetURL() override;
   bool IsInMainFrame() override;
   const base::TimeTicks& NavigationStart() override;
   bool IsPost() override;
   const Referrer& GetReferrer() override;
   bool HasUserGesture() override;
   ui::PageTransition GetPageTransition() override;
@@ skipping 21 matching lines @@
       bool new_is_external_protocol) override;
 
   NavigatorDelegate* GetDelegate() const;
 
   // Returns the response headers for the request. This can only be accessed
   // after a redirect was encountered or after the the navigation is ready to
   // commit. It should not be modified, as modifications will not be reflected
   // in the network stack.
   const net::HttpResponseHeaders* GetResponseHeaders();
 
+  int get_entry_id() { return entry_id_; }

[Charlie Reis, 2016/02/05 19:36:11]

nit: Maybe nav_entry_id(), as in RenderFrameHostImpl?

This would also benefit from a comment about when it's valid, that it's 0 for
invalid, and whether it can change over time.

[Charlie Harrison, 2016/02/05 23:10:23]

I don't *think* it can change over time, so I'll mark it const (and make the
function const too, why not) + added a comment.

+
   void set_net_error_code(net::Error net_error_code) {
     net_error_code_ = net_error_code;
   }
 
   // Returns whether the navigation is currently being transferred from one
   // RenderFrameHost to another. In particular, a DidStartProvisionalLoad IPC
   // for the navigation URL, received in the new RenderFrameHost, should not
   // indicate the start of a new navigation in that case.
   bool is_transferring() const { return is_transferring_; }
   void set_is_transferring(bool is_transferring) {
@@ skipping 69 matching lines @@
     WILL_REDIRECT_REQUEST,
     DEFERRING_REDIRECT,
     CANCELING,
     READY_TO_COMMIT,
     DID_COMMIT,
     DID_COMMIT_ERROR_PAGE,
   };
 
   NavigationHandleImpl(const GURL& url,
                        FrameTreeNode* frame_tree_node,
-                       const base::TimeTicks& navigation_start);
+                       const base::TimeTicks& navigation_start,
+                       NavigationEntry* navigation_entry);
 
   NavigationThrottle::ThrottleCheckResult CheckWillStartRequest();
   NavigationThrottle::ThrottleCheckResult CheckWillRedirectRequest();
 
   // Helper function to run and reset the |complete_callback_|. This marks the
   // end of a round of NavigationThrottleChecks.
   void RunCompleteCallback(NavigationThrottle::ThrottleCheckResult result);
 
   // Used in tests.
   State state() const { return state_; }
@@ skipping 22 matching lines @@
 
   // A list of Throttles registered for this navigation.
   ScopedVector<NavigationThrottle> throttles_;
 
   // The index of the next throttle to check.
   size_t next_index_;
 
   // The time this navigation started.
   const base::TimeTicks navigation_start_;
 
+  // The unique id of the corresponding NavigationEntry.
+  int entry_id_;
+
   // This callback will be run when all throttle checks have been performed.
   ThrottleChecksFinishedCallback complete_callback_;
 
   // PlzNavigate
   // Manages the lifetime of a pre-created ServiceWorkerProviderHost until a
   // corresponding ServiceWorkerNetworkProvider is created in the renderer.
   scoped_ptr<ServiceWorkerNavigationHandle> service_worker_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_