Check that render-frame is valid before returning audio params in Blink.

content/renderer/renderer_blink_platform_impl.cc

Index: content/renderer/renderer_blink_platform_impl.cc
diff --git a/content/renderer/renderer_blink_platform_impl.cc b/content/renderer/renderer_blink_platform_impl.cc
index c616aa7b5a85b4b48d7a4291c6ff1afeeb951018..9a06e8893788189ef6c428b9a55d3bb61c732163 100644
--- a/content/renderer/renderer_blink_platform_impl.cc
+++ b/content/renderer/renderer_blink_platform_impl.cc
@@ -180,6 +180,9 @@ media::AudioParameters GetAudioHardwareParams() {
   blink::WebLocalFrame* const web_frame =
       blink::WebLocalFrame::frameForCurrentContext();
   RenderFrame* const render_frame = RenderFrame::FromWebFrame(web_frame);
+  if (!render_frame)
+    return media::AudioParameters::UnavailableDeviceParams();
+
   return AudioDeviceFactory::GetOutputDeviceInfo(render_frame->GetRoutingID(),
                                                  0, std::string(),
                                                  web_frame->getSecurityOrigin())