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 25f3249d44ebdebd041ab9ff1eb06b1daeed344c..428d2aa0cb216ac6bf386db22d749ef08f03716d 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -862,6 +862,10 @@ 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());