Display DNS probe results.

chrome/renderer/net/net_error_helper.h

 // Copyright (c) 2013 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 CHROME_RENDERER_NET_NET_ERROR_HELPER_H_
 #define CHROME_RENDERER_NET_NET_ERROR_HELPER_H_
 
+#include <string>
+
 #include "chrome/common/net/net_error_info.h"
-#include "chrome/common/net/net_error_tracker.h"
 #include "content/public/renderer/render_view_observer.h"
+#include "third_party/WebKit/public/platform/WebURLError.h"
+
+namespace base {
+class DictionaryValue;
+}
 
 namespace WebKit {
 class WebFrame;
 }
 
+// Listens for NetErrorInfo messages from the NetErrorTabHelper on the
+// browser side and updates the error page with more details (currently, just
+// DNS probe results) if/when available.
 class NetErrorHelper : public content::RenderViewObserver {
  public:
   explicit NetErrorHelper(content::RenderView* render_view);
   virtual ~NetErrorHelper();
 
   // RenderViewObserver implementation.
   virtual void DidStartProvisionalLoad(WebKit::WebFrame* frame) OVERRIDE;
   virtual void DidFailProvisionalLoad(
       WebKit::WebFrame* frame,
       const WebKit::WebURLError& error) OVERRIDE;
   virtual void DidCommitProvisionalLoad(
       WebKit::WebFrame* frame,
       bool is_new_navigation) OVERRIDE;
   virtual void DidFinishLoad(WebKit::WebFrame* frame) OVERRIDE;
 
   // IPC::Listener implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
+  // Examines |frame| and |error| to see if this is an error worthy of a DNS
+  // probe.  If it is, initializes |error_strings| based on |error|,
+  // |is_failed_post|, and |locale| with suitable strings and returns true.
+  // If not, returns false, in which case the caller should look up error
+  // strings directly using LocalizedError::GetNavigationErrorStrings.
+  static bool GetErrorStringsForDnsProbe(
+      WebKit::WebFrame* frame,
+      const WebKit::WebURLError& error,
+      bool is_failed_post,
+      const std::string& locale,
+      base::DictionaryValue* error_strings);
+
+ protected:
+  // These methods handle tracking the actual state of the page; this allows
+  // unit-testing of the state tracking without having to mock out WebFrames
+  // and such.
+  void OnStartLoad(bool is_main_frame, bool is_error_page);
+  void OnFailLoad(bool is_main_frame, bool is_dns_error);
+  void OnCommitLoad(bool is_main_frame);
+  void OnFinishLoad(bool is_main_frame);
+
+  void OnNetErrorInfo(int status);
+  virtual void UpdateErrorPage();

[James Hawkins, 2013/07/15 19:52:45]

What is this an implementation of?

[Deprecated (see juliatuttle), 2013/07/15 20:22:28]

It's not.  UpdateErrorPage is virtual so we can mock it out in a subclass for
unittesting.

[James Hawkins, 2013/07/15 20:28:31]

Please document that.

+
+  // The last DnsProbeStatus received from the browser.
+  chrome_common_net::DnsProbeStatus last_probe_status_;
+
  private:
-  void OnNetErrorInfo(int dns_probe_result);
-  void TrackerCallback(NetErrorTracker::DnsErrorPageState state);
-  void UpdateErrorPage(chrome_common_net::DnsProbeResult dns_probe_result);
+  WebKit::WebURLError GetUpdatedError() const;
 
-  NetErrorTracker tracker_;
-  NetErrorTracker::DnsErrorPageState dns_error_page_state_;
-  bool updated_error_page_;
+  // Whether the last provisional load started was for an error page.
+  bool last_start_was_error_page_;
+
+  // Whether the last provisional load failure failed with a DNS error.
+  bool last_fail_was_dns_error_;
+
+  // This is an odd variable.

[James Hawkins, 2013/07/15 19:52:45]

Optional nit: Remove this part of the comment; it starts the reading off w/
confusion.

[Deprecated (see juliatuttle), 2013/07/15 20:22:28]

Done.

+  //
+  // Ideally, it would be simply "last_commit_was_dns_error_page_".
+  //
+  // Unfortunately, that breaks if two DNS errors occur in a row; after the
+  // second failure, but before the second page commits, the helper can receive
+  // probe results.  If all it knows is that the last commit was a DNS error
+  // page, it will cheerfully forward the results for the second probe to the
+  // first page.
+  //
+  // Thus, the semantics of this flag are a little weird.  It is set whenever
+  // a DNS error page commits, and cleared whenever any other page commits,
+  // but it is also cleared whenever a DNS error occurs, to prevent the race
+  // described above.
+  bool forwarding_probe_results_;
+
+  // The last main frame error seen by the helper.
+  WebKit::WebURLError last_error_;
+
   bool is_failed_post_;
 };
 
 #endif  // CHROME_RENDERER_NET_NET_ERROR_HELPER_H_