VrShell: Exit fullscreen on app button press.

chrome/browser/android/vr_shell/vr_gl_thread.cc

Index: chrome/browser/android/vr_shell/vr_gl_thread.cc
diff --git a/chrome/browser/android/vr_shell/vr_gl_thread.cc b/chrome/browser/android/vr_shell/vr_gl_thread.cc
index ba43e68136dfff93f795ffb4eec9fcf168e64643..386a3e17e8b4b298a94737c83ede5e6801779bbc 100644
--- a/chrome/browser/android/vr_shell/vr_gl_thread.cc
+++ b/chrome/browser/android/vr_shell/vr_gl_thread.cc
@@ -91,6 +91,11 @@ void VrGLThread::ExitPresent() {
       FROM_HERE, base::Bind(&VrShell::ExitPresent, weak_vr_shell_));
 }
 
+void VrGLThread::ExitFullscreen() {
+  main_thread_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&VrShell::ExitFullscreen, weak_vr_shell_));
+}
+
 void VrGLThread::RunVRDisplayInfoCallback(
     const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
     device::mojom::VRDisplayInfoPtr* info) {