Fix VR Shell crashing when renderer crashes or native page is shown.

chrome/browser/android/vr_shell/vr_input_manager.cc

Index: chrome/browser/android/vr_shell/vr_input_manager.cc
diff --git a/chrome/browser/android/vr_shell/vr_input_manager.cc b/chrome/browser/android/vr_shell/vr_input_manager.cc
index 5b54eca62c32dbd4051fafbedfa3764d288b98b4..fad21cf3b214fae4ac08c583f0b2f1a3d040f761 100644
--- a/chrome/browser/android/vr_shell/vr_input_manager.cc
+++ b/chrome/browser/android/vr_shell/vr_input_manager.cc
@@ -80,6 +80,8 @@ WebGestureEvent VrInputManager::MakeGestureEvent(WebInputEvent::Type type,
 
 void VrInputManager::ForwardGestureEvent(
     const blink::WebGestureEvent& gesture) {
+  if (!web_contents_->GetRenderWidgetHostView())
+    return;
   content::RenderWidgetHost* rwh =
       web_contents_->GetRenderWidgetHostView()->GetRenderWidgetHost();
   if (rwh)
@@ -88,6 +90,8 @@ void VrInputManager::ForwardGestureEvent(
 
 void VrInputManager::ForwardMouseEvent(
     const blink::WebMouseEvent& mouse_event) {
+  if (!web_contents_->GetRenderWidgetHostView())
+      return;
   content::RenderWidgetHost* rwh =
       web_contents_->GetRenderWidgetHostView()->GetRenderWidgetHost();
   if (rwh)