Implement a MusBrowserFrame.

chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc

Index: chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc
diff --git a/chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc b/chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc
index 3a30309c47f734f6e591bfbf21818b616d851d56..1f42d7edc2707fbeb5a6b308436a501da43736dc 100644
--- a/chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc
+++ b/chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc
@@ -4,10 +4,19 @@
 
 #include "chrome/browser/ui/views/frame/native_browser_frame_factory.h"
 
+#include "chrome/browser/mojo_runner_util.h"
 #include "chrome/browser/ui/views/frame/browser_frame_ash.h"
 
+#if defined(MOJO_RUNNER_CLIENT)
+#include "chrome/browser/ui/views/frame/browser_frame_mus.h"
+#endif
+
 NativeBrowserFrame* NativeBrowserFrameFactory::Create(
     BrowserFrame* browser_frame,
     BrowserView* browser_view) {
+#if defined(MOJO_RUNNER_CLIENT)
+  if (IsRunningInMojoRunner())
+    return new BrowserFrameMus(browser_frame, browser_view);
+#endif
   return new BrowserFrameAsh(browser_frame, browser_view);
 }