Add comment about same-page navs to WCO::DidStart/FinishNavigation

content/public/browser/web_contents_observer.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 125 matching lines @@
   // Called when a navigation started in the WebContents. |navigation_handle|
   // is unique to a specific navigation. The same |navigation_handle| will be
   // provided on subsequent calls to DidRedirectNavigation, DidFinishNavigation,
   // and ReadyToCommitNavigation when related to this navigation. Observers
   // should clear any references to |navigation_handle| in DidFinishNavigation,
   // just before it is destroyed.
   //
   // Note that this is fired by navigations in any frame of the WebContents,
   // not just the main frame.
   //
+  // Note that this is fired by same-page navigations, such as fragment
+  // navigations or pushState/replaceState, which will not result in a document
+  // change. To filter these out, use NavigationHandle::IsSamePage.
+  //
   // Note that more than one navigation can be ongoing in the same frame at the
   // same time (including the main frame). Each will get its own
   // NavigationHandle.
   //
   // Note that there is no guarantee that DidFinishNavigation will be called
   // for any particular navigation before DidStartNavigation is called on the
   // next.
   virtual void DidStartNavigation(NavigationHandle* navigation_handle) {}
 
   // Called when a navigation encountered a server redirect.
@@ skipping 15 matching lines @@
   // navigation has committed, use NavigationHandle::HasCommitted; use
   // NavigationHandle::IsErrorPage to know if the navigation resulted in an
   // error page.
   //
   // If this is called because the navigation committed, then the document load
   // will still be ongoing in the RenderFrameHost returned by
   // |navigation_handle|. Use the document loads events such as DidStopLoading
   // and related methods to listen for continued events from this
   // RenderFrameHost.
   //
+  // Note that this is fired by same-page navigations, such as fragment
+  // navigations or pushState/replaceState, which will not result in a document
+  // change. To filter these out, use NavigationHandle::IsSamePage.
+  //
   // Note that |navigation_handle| will be destroyed at the end of this call,
   // so do not keep a reference to it afterward.
   virtual void DidFinishNavigation(NavigationHandle* navigation_handle) {}
 
   // Navigation (obsolete and deprecated) --------------------------------------
 
   // This method is invoked after the browser process starts a navigation to a
   // pending NavigationEntry. It is not called for renderer-initiated
   // navigations unless they are sent to the browser process via OpenURL. It may
   // be called multiple times for a given navigation, such as a typed URL
@@ skipping 322 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_