Instant: Fix a crash where the tab is closing and Instant 'hides' the

underlying TabContents. |render_widget_host_| is NULL as
RenderWidgetHostViewWin is being destroyed.

BUG=101948
TEST=none

R=sky@chromium.org

Review URL: http://codereview.chromium.org/8418005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107655 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/render_widget_host_view_win.cc

@@ -347,7 +347,8 @@ void RenderWidgetHostViewWin::WasHidden() {
 
   // If we have a renderer, then inform it that we are being hidden so it can
   // reduce its resource utilization.
-  render_widget_host_->WasHidden();
+  if (render_widget_host_)
+    render_widget_host_->WasHidden();
 }
 
 void RenderWidgetHostViewWin::SetSize(const gfx::Size& size) {