Implement lazy initialization for VrShellDelegate

chrome/browser/android/vr_shell/vr_shell_delegate.cc

Index: chrome/browser/android/vr_shell/vr_shell_delegate.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_delegate.cc b/chrome/browser/android/vr_shell/vr_shell_delegate.cc
index a25b6a513e19f90feaf80bb77c62485cb3b9d239..b230390cb77077b00a1f2fa858cdc218fc1422f6 100644
--- a/chrome/browser/android/vr_shell/vr_shell_delegate.cc
+++ b/chrome/browser/android/vr_shell/vr_shell_delegate.cc
@@ -21,16 +21,23 @@ namespace vr_shell {
 VrShellDelegate::VrShellDelegate(JNIEnv* env, jobject obj)
     : weak_ptr_factory_(this) {
   j_vr_shell_delegate_.Reset(env, obj);
-  GvrDelegateProvider::SetInstance(this);
 }
 
 VrShellDelegate::~VrShellDelegate() {
-  GvrDelegateProvider::SetInstance(nullptr);
   if (device_provider_) {
     device_provider_->Device()->OnDelegateChanged();
   }
 }
 
+device::GvrDelegateProvider* VrShellDelegate::CreateVrShellDelegate() {
+  JNIEnv* env = AttachCurrentThread();
+  base::android::ScopedJavaLocalRef<jobject> jdelegate =
+      Java_VrShellDelegate_getInstance(env);
+  if (!jdelegate.is_null())
+    return GetNativeVrShellDelegate(env, jdelegate.obj());

[amp, 2017/03/02 18:11:54]

It looks it's possible for jdelegate to be non null, but it hasn't initialized
the native vr shell delegate yet (if vr was not available it will construct a
basic java vr shell delegate, but return before initializing native).

[mthiesse, 2017/03/02 20:01:58]

Fixed. jdelegate is never null now.

+  return nullptr;
+}
+
 VrShellDelegate* VrShellDelegate::GetNativeVrShellDelegate(JNIEnv* env,
                                                            jobject jdelegate) {
   return reinterpret_cast<VrShellDelegate*>(
@@ -115,6 +122,10 @@ void VrShellDelegate::OnResume(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   }
 }
 
+void VrShellDelegate::Destroy(JNIEnv* env, const JavaParamRef<jobject>& obj) {
+  delete this;
+}
+
 void VrShellDelegate::ShowTab(int id) {
   JNIEnv* env = AttachCurrentThread();
   Java_VrShellDelegate_showTab(env, j_vr_shell_delegate_.obj(), id);
@@ -208,4 +219,9 @@ jlong Init(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   return reinterpret_cast<intptr_t>(new VrShellDelegate(env, obj));
 }
 
+static void OnLibraryAvailable(JNIEnv* env, const JavaParamRef<jclass>& clazz) {
+  device::GvrDelegateProvider::SetInstance(
+      base::Bind(&VrShellDelegate::CreateVrShellDelegate));
+}
+
 }  // namespace vr_shell