Fix re-usage of stale cached WebPreferences in RenderViewHost.

content/shell/browser/layout_test/blink_test_controller.cc

Index: content/shell/browser/layout_test/blink_test_controller.cc
diff --git a/content/shell/browser/layout_test/blink_test_controller.cc b/content/shell/browser/layout_test/blink_test_controller.cc
index 02d0af00688bf14a82b7ff74849d786cae78a1f7..2c45643ade420f22757206dae410a7119192bddf 100644
--- a/content/shell/browser/layout_test/blink_test_controller.cc
+++ b/content/shell/browser/layout_test/blink_test_controller.cc
@@ -762,6 +762,12 @@ void BlinkTestController::OnPrintMessage(const std::string& message) {
 void BlinkTestController::OnOverridePreferences(const WebPreferences& prefs) {
   should_override_prefs_ = true;
   prefs_ = prefs;
+
+  // Notifies the main RenderViewHost that Blink preferences changed so to avoid
+  // re-usage of cached preferences that are now stale.
+  RenderViewHost* main_render_view_host =
+      main_window_->web_contents()->GetRenderViewHost();
+  main_render_view_host->OnWebkitPreferencesChanged();
 }
 
 void BlinkTestController::OnClearDevToolsLocalStorage() {