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 e7cafaa8e96ec39bd57346bdbc5e9e1aa41db888..4503a8c84989d1025a0a3f26ad2a1f40aad647f2 100644
--- a/chrome/browser/android/vr_shell/vr_gl_thread.cc
+++ b/chrome/browser/android/vr_shell/vr_gl_thread.cc
@@ -86,6 +86,11 @@ void VrGLThread::ForceExitVr() {
       FROM_HERE, base::Bind(&VrShell::ForceExitVr, 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) {