PlzNavigate: Invoke didStartProvisionalLoad() when the renderer initiates a navigation in startLoad(

content/renderer/render_frame_impl.h

 // 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.
 
 #ifndef CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 #define CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 531 matching lines @@
                          const blink::WebString& suggested_name,
                          bool should_replace_current_entry) override;
   void loadErrorPage(int reason) override;
   blink::WebNavigationPolicy decidePolicyForNavigation(
       const NavigationPolicyInfo& info) override;
   blink::WebHistoryItem historyItemForNewChildFrame() override;
   void willSendSubmitEvent(const blink::WebFormElement& form) override;
   void willSubmitForm(const blink::WebFormElement& form) override;
   void didCreateDataSource(blink::WebLocalFrame* frame,
                            blink::WebDataSource* datasource) override;
-  void didStartProvisionalLoad(blink::WebLocalFrame* frame) override;
+  void didStartProvisionalLoad(blink::WebDataSource* data_source) override;
   void didReceiveServerRedirectForProvisionalLoad(
       blink::WebLocalFrame* frame) override;
   void didFailProvisionalLoad(blink::WebLocalFrame* frame,
                               const blink::WebURLError& error,
                               blink::WebHistoryCommitType commit_type) override;
   void didCommitProvisionalLoad(
       blink::WebLocalFrame* frame,
       const blink::WebHistoryItem& item,
       blink::WebHistoryCommitType commit_type) override;
   void didCreateNewDocument(blink::WebLocalFrame* frame) override;
@@ skipping 828 matching lines @@
   int enabled_bindings_ = 0;
 
   base::WeakPtrFactory<RenderFrameImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_IMPL_H_