Add way to get native VR UI information from Java

chrome/browser/android/vr_shell/vr_shell.cc

Index: chrome/browser/android/vr_shell/vr_shell.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell.cc b/chrome/browser/android/vr_shell/vr_shell.cc
index 904c41ab5931df6aaaee0b74396c96a55f7df0b4..1580024d0155dfd68120ae9f48b696293a329887 100644
--- a/chrome/browser/android/vr_shell/vr_shell.cc
+++ b/chrome/browser/android/vr_shell/vr_shell.cc
@@ -9,7 +9,9 @@
 #include <string>
 #include <utility>
 
+#include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
+#include "base/json/json_writer.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/platform_thread.h"
@@ -419,6 +421,19 @@ void VrShell::SetHistoryButtonsEnabled(JNIEnv* env,
   html_interface_->SetHistoryButtonsEnabled(can_go_back, can_go_forward);
 }
 
+void VrShell::RequestUiElementInfoForTesting(JNIEnv* env,
+                                             const JavaParamRef<jobject>& obj,
+                                             jobjectArray element_names) {
+  std::vector<std::string> element_names_vector;
+  base::android::AppendJavaStringArrayToStringVector(env, element_names,
+                                                     &element_names_vector);
+  PostToGlThreadWhenReady(
+      base::Bind(&VrShellGl::CreateUiElementInfos, gl_thread_->GetVrShellGl(),
+                 element_names_vector,
+                 base::Bind(&VrShell::OnUiElementInfoCreated,
+                            weak_ptr_factory_.GetWeakPtr())));
+}
+
 void VrShell::UiSurfaceChanged(jobject surface) {
   ui_compositor_->SurfaceChanged(surface);
 }
@@ -561,6 +576,16 @@ void VrShell::DoUiAction(const UiAction action,
   }
 }
 
+void VrShell::OnUiElementInfoCreated(
+    std::unique_ptr<base::DictionaryValue> info) {
+  std::string json_reply;
+  base::JSONWriter::Write(*info, &json_reply);
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_VrShellImpl_replyToUiElementInfoRequestForTesting(
+      env, j_vr_shell_.obj(),
+      base::android::ConvertUTF8ToJavaString(env, json_reply));
+}
+
 void VrShell::RenderViewHostChanged(content::RenderViewHost* old_host,
                                     content::RenderViewHost* new_host) {
   content::RenderWidgetHostView* view = new_host->GetWidget()->GetView();