Remove use of WebContentsImpl from ResourceDispatcherHostImpl

To reduce dependencies from content/browser/loader to the rest of
content. Follows https://codereview.chromium.org/2098923002/.

[email protected], [email protected]
BUG=598073

Review-Url: https://codereview.chromium.org/2108643004
Cr-Commit-Position: refs/heads/master@{#403036}
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index da86a77..6c3d49a9 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -4580,7 +4580,7 @@
   // Exclude scroll events as user gestures for resource load dispatches.
   // rdh is NULL in unittests.
   if (rdh && type != blink::WebInputEvent::MouseWheel)
-    rdh->OnUserGesture(this);
+    rdh->OnUserGesture();
 }
 
 void WebContentsImpl::OnIgnoredUIEvent() {