Fix several issues with VR instrumentation tests

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
index 14a01769f01c9f1f275b1fc17840d8bbedfb96f3..9c98d5d356975c1538f2290f510e3142d8429e07 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
@@ -722,7 +722,12 @@ public class VrShellDelegate {
         if (mVrClassesWrapper == null) return false;
         mTabModelSelector = mActivity.getCompositorViewHolder().detachForVR();
         if (mTabModelSelector == null) return false;
-        mVrShell = mVrClassesWrapper.createVrShell(mActivity, this, mTabModelSelector);
+        StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskWrites();
+        try {
+            mVrShell = mVrClassesWrapper.createVrShell(mActivity, this, mTabModelSelector);
+        } finally {
+            StrictMode.setThreadPolicy(oldPolicy);
+        }
         return mVrShell != null;
     }