GTK: Speculative fix for crash in BalloonViewHost.

chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc

Index: chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc
diff --git a/chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc b/chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc
index ee44ae8f0ca65aed6c28d74d4e30311570e9b4e7..af7f91c95df0631d8d091284481d74a99f62dd7e 100644
--- a/chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc
+++ b/chrome/browser/ui/gtk/notifications/balloon_view_host_gtk.cc
@@ -18,7 +18,13 @@ BalloonViewHost::~BalloonViewHost() {
 }
 
 void BalloonViewHost::UpdateActualSize(const gfx::Size& new_size) {
-  tab_contents_->render_view_host()->view()->SetSize(new_size);
+  RenderViewHost* host = tab_contents_->render_view_host();
+  if (host) {
+    RenderWidgetHostView* view = host->view();
+    if (view)
+      view->SetSize(new_size);
+  }
+
   gtk_widget_set_size_request(
       native_view(), new_size.width(), new_size.height());
 }