Use VrClassesBuilder to reduce reflection usage

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

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrClassesBuilderImpl.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrClassesBuilderImpl.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrClassesBuilderImpl.java
new file mode 100644
index 0000000000000000000000000000000000000000..163ffa68875efdb0538d5979392996f464ffcfbd
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrClassesBuilderImpl.java
@@ -0,0 +1,43 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.vr_shell;
+
+import android.app.Activity;
+
+import org.chromium.base.annotations.UsedByReflection;
+
+/**
+ * Builder class to create all VR related classes. These VR classes are behind the same build time
+ * flag as this class. So no reflection is necessary when create them.
+ */
+@UsedByReflection("VrShellDelegate.java")
+public class VrClassesBuilderImpl implements VrClassesBuilder {
+    private final Activity mActivity;
+
+    @UsedByReflection("VrShellDelegate.java")
+    public VrClassesBuilderImpl(Activity activity) {
+        mActivity = activity;
+    }
+
+    @Override
+    public NonPresentingGvrContext createNonPresentingGvrContext() {
+        return new NonPresentingGvrContextImpl(mActivity);
+    }
+
+    @Override
+    public VrShell createVrShell() {
+        return new VrShellImpl(mActivity);
+    }
+
+    @Override
+    public VrDaydreamApi createVrDaydreamApi() {
+        return new VrDaydreamApiImpl(mActivity);
+    }
+
+    @Override
+    public VrCoreVersionChecker createVrCoreVersionChecker() {
+        return new VrCoreVersionCheckerImpl();
+    }
+}