Wire up download attribution enable finch experiment

chrome/browser/safe_browsing/safe_browsing_navigation_observer.h

 // Copyright 2016 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_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_H_
 
 #include "base/supports_user_data.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "url/gurl.h"
@@ skipping 46 matching lines @@
       : timestamp(timestamp), ip(ip) {}
   base::Time timestamp;  // Timestamp of when we get the resolved IP.
   std::string ip;        // Resolved IP address
 };
 
 // Observes the navigation events for a single WebContents (both main-frame
 // and sub-frame navigations).
 class SafeBrowsingNavigationObserver : public base::SupportsUserData::Data,
                                        public content::WebContentsObserver {
  public:
-  static void MaybeCreateForWebContents(content::WebContents* web_contents);
+  static void CreateForWebContents(
+      content::WebContents* web_contents,
+      const scoped_refptr<SafeBrowsingNavigationObserverManager>& manager);
+
   static SafeBrowsingNavigationObserver* FromWebContents(
       content::WebContents* web_contents);
 
   SafeBrowsingNavigationObserver(
       content::WebContents* contents,
       const scoped_refptr<SafeBrowsingNavigationObserverManager>& manager);
 
   ~SafeBrowsingNavigationObserver() override;
 
  private:
@@ skipping 26 matching lines @@
   bool has_user_gesture_;
 
   base::Time last_user_gesture_timestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingNavigationObserver);
 };
 
 }  // namespace safe_browsing
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_H_