Update viewport_meta setting on any navigation.

content/test/test_render_view_host.cc

Index: content/test/test_render_view_host.cc
diff --git a/content/test/test_render_view_host.cc b/content/test/test_render_view_host.cc
index 49a80a0d8bf76a081f818b1bc50bf8353b0ce2e1..b03f7b89436d274fd7310f1dd92e87918c55bbcc 100644
--- a/content/test/test_render_view_host.cc
+++ b/content/test/test_render_view_host.cc
@@ -239,6 +239,7 @@ TestRenderViewHost::TestRenderViewHost(
                          swapped_out,
                          false /* has_initialized_audio_host */),
       delete_counter_(nullptr),
+      webkit_preferences_changed_counter_(nullptr),
       opener_frame_route_id_(MSG_ROUTING_NONE) {
   // TestRenderWidgetHostView installs itself into this->view_ in its
   // constructor, and deletes itself when TestRenderWidgetHostView::Destroy() is
@@ -294,6 +295,12 @@ WebPreferences TestRenderViewHost::TestComputeWebkitPrefs() {
   return ComputeWebkitPrefs();
 }
 
+void TestRenderViewHost::OnWebkitPreferencesChanged() {
+  RenderViewHostImpl::OnWebkitPreferencesChanged();
+  if (webkit_preferences_changed_counter_)
+    ++*webkit_preferences_changed_counter_;
+}
+
 void TestRenderViewHost::TestOnStartDragging(
     const DropData& drop_data) {
   blink::WebDragOperationsMask drag_operation = blink::WebDragOperationEvery;