Fix regression of webview loadstart events firing for same page navigations.

extensions/browser/guest_view/web_view/web_view_guest.cc

Index: extensions/browser/guest_view/web_view/web_view_guest.cc
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index d02f9fc02b78c6a8ef95c231bfc09cba41894d60..8266ea2a93b92b416ab4476eb69e77eec1d59fc3 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -860,6 +860,10 @@ void WebViewGuest::DidFinishNavigation(
 
 void WebViewGuest::DidStartNavigation(
     content::NavigationHandle* navigation_handle) {
+  // loadStart shouldn't be sent for same page navigations.
+  if (navigation_handle->IsSamePage())
+    return;
+
   std::unique_ptr<base::DictionaryValue> args(new base::DictionaryValue());
   args->SetString(guest_view::kUrl, navigation_handle->GetURL().spec());
   args->SetBoolean(guest_view::kIsTopLevel, navigation_handle->IsInMainFrame());