Better distinguish didFinishLoad and didStopLoading

chrome/browser/extensions/api/web_navigation/web_navigation_api.cc

 // Copyright (c) 2012 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.
 
 // Implements the Chrome Extensions WebNavigation API.
 
 #include "chrome/browser/extensions/api/web_navigation/web_navigation_api.h"
 
 #include "base/lazy_instance.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 380 matching lines @@
            << "render_frame_host=" << render_frame_host
            << ", frame_num=" << render_frame_host->GetRoutingID()
            << ", url=" << validated_url << ")";
   // When showing replacement content, we might get load signals for frames
   // that weren't reguarly loaded.
   if (!navigation_state_.IsValidFrame(render_frame_host))
     return;
   navigation_state_.SetNavigationCompleted(render_frame_host);
   if (!navigation_state_.CanSendEvents(render_frame_host))
     return;
-  DCHECK(navigation_state_.GetUrl(render_frame_host) == validated_url ||
-         (navigation_state_.GetUrl(render_frame_host) ==
-              GURL(content::kAboutSrcDocURL) &&
-          validated_url == GURL(url::kAboutBlankURL)))
-      << "validated URL is " << validated_url << " but we expected "
-      << navigation_state_.GetUrl(render_frame_host);
+
+  // A new navigation might have started before the old one completed.
+  // Ignore the old navigation completion in that case.
+  // srcdoc iframes will report a url of about:blank, still let it through.
+  if (navigation_state_.GetUrl(render_frame_host) != validated_url &&
+      (navigation_state_.GetUrl(render_frame_host) !=
+           GURL(content::kAboutSrcDocURL) ||
+       validated_url != GURL(url::kAboutBlankURL))) {
+    return;

[nasko, 2015/10/12 23:48:24]

Does your change imply that a DidFailLoad will be called if we start a new
provisional load before DidFinishLoad is called? Or would we call DidFailLoad
only when the provisional load is ready for commit?
I'm trying to understand the exact sequence of events that was hitting this
CHECK and how it will behave with your changes.

+  }
 
   // The load might already have finished by the time we finished parsing. For
   // compatibility reasons, we artifically delay the load completed signal until
   // after parsing was completed.
   if (!navigation_state_.GetParsingFinished(render_frame_host))
     return;
   helpers::DispatchOnCompleted(web_contents(),
                                render_frame_host,
                                navigation_state_.GetUrl(render_frame_host));
 }
@@ skipping 208 matching lines @@
   return g_factory.Pointer();
 }
 
 void WebNavigationAPI::OnListenerAdded(const EventListenerInfo& details) {
   web_navigation_event_router_.reset(new WebNavigationEventRouter(
       Profile::FromBrowserContext(browser_context_)));
   EventRouter::Get(browser_context_)->UnregisterObserver(this);
 }
 
 }  // namespace extensions