Remove AboutToNavigateRenderFrame, issue custom notification for DevTools.

content/browser/frame_host/navigator_impl.cc

 // Copyright 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.
 
 #include "content/browser/frame_host/navigator_impl.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/time/time.h"
 #include "content/browser/frame_host/frame_tree.h"
@@ skipping 302 matching lines @@
   if (!dest_render_frame_host)
     return false;  // Unable to create the desired RenderFrameHost.
 
   // Make sure no code called via RFHM::Navigate clears the pending entry.
   CHECK_EQ(controller_->GetPendingEntry(), &entry);
 
   // For security, we should never send non-Web-UI URLs to a Web UI renderer.
   // Double check that here.
   CheckWebUIRendererDoesNotDisplayNormalURL(dest_render_frame_host, dest_url);
 
-  // Notify observers that we will navigate in this RenderFrame.
-  if (delegate_) {
-    delegate_->AboutToNavigateRenderFrame(frame_tree_node->current_frame_host(),
-                                          dest_render_frame_host);
-  }
-
   // Navigate in the desired RenderFrameHost.
   // We can skip this step in the rare case that this is a transfer navigation
   // which began in the chosen RenderFrameHost, since the request has already
   // been issued.  In that case, simply resume the response.
   bool is_transfer_to_same =
       entry.transferred_global_request_id().child_id != -1 &&
       entry.transferred_global_request_id().child_id ==
           dest_render_frame_host->GetProcess()->GetID();
   if (!is_transfer_to_same) {
     navigation_data_.reset(new NavigationMetricsData(navigation_start, dest_url,
@@ skipping 613 matching lines @@
       entry->set_should_replace_entry(pending_entry->should_replace_entry());
       entry->SetRedirectChain(pending_entry->GetRedirectChain());
     }
     controller_->SetPendingEntry(entry.Pass());
     if (delegate_)
       delegate_->NotifyChangedNavigationState(content::INVALIDATE_TYPE_URL);
   }
 }
 
 }  // namespace content