Add way to get native VR UI information from Java

chrome/browser/android/vr_shell/vr_shell.cc

 // 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.
 
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 
 #include <android/native_window_jni.h>
 
 #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"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "chrome/browser/android/tab_android.h"
 #include "chrome/browser/android/vr_shell/android_ui_gesture_target.h"
 #include "chrome/browser/android/vr_shell/vr_compositor.h"
@@ skipping 367 matching lines @@
       base::Bind(&VrShellGl::CreateContentSurface, gl_thread_->GetVrShellGl()));
 }
 
 void VrShell::SetHistoryButtonsEnabled(JNIEnv* env,
                                        const JavaParamRef<jobject>& obj,
                                        jboolean can_go_back,
                                        jboolean can_go_forward) {
   html_interface_->SetHistoryButtonsEnabled(can_go_back, can_go_forward);
 }
 
+void VrShell::RequestUiElementInfo(JNIEnv* env,
+                                   const JavaParamRef<jobject>& obj,
+                                   jintArray element_ids,
+                                   jint callback_id) {
+  std::vector<int> element_ids_vector;
+  base::android::JavaIntArrayToIntVector(env, element_ids, &element_ids_vector);
+  PostToGlThreadWhenReady(
+      base::Bind(&VrShellGl::CreateUiElementInfos, gl_thread_->GetVrShellGl(),
+                 element_ids_vector, callback_id,
+                 base::Bind(&VrShell::OnUiElementInfoCreated,
+                            weak_ptr_factory_.GetWeakPtr())));
+}
+
 void VrShell::UiSurfaceChanged(jobject surface) {
   ui_compositor_->SurfaceChanged(surface);
 }
 
 void VrShell::ContentSurfaceChanged(jobject surface) {
   content_surface_ = surface;
   content_compositor_->SurfaceChanged(surface);
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_VrShellImpl_contentSurfaceChanged(env, j_vr_shell_.obj());
 }
@@ skipping 122 matching lines @@
           base::android::ConvertUTF16ToJavaString(env, url_string);
       Java_VrShellImpl_loadURL(env, j_vr_shell_.obj(), string,
                                ui::PageTransition::PAGE_TRANSITION_TYPED);
       break;
     }
     default:
       NOTREACHED();
   }
 }
 
+void VrShell::OnUiElementInfoCreated(
+    int callback_id,
+    std::unique_ptr<base::DictionaryValue> info) {
+  std::string json_reply;
+  base::JSONWriter::Write(*info, &json_reply);

[bsheedy, 2017/03/24 18:47:54]

Converting to a JSON string in native then back to an object in Java doesn't
seem like the ideal approach, but I'm not aware of a better way to get a
base::Value type back to Java.

[tiborg, 2017/03/27 15:14:33]

I'm not aware of a better solution either. I think it is suitable for testing.

+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_VrShellImpl_replyToUiElementInfoRequest(
+      env, j_vr_shell_.obj(),
+      base::android::ConvertUTF8ToJavaString(env, json_reply), callback_id);
+}
+
 void VrShell::RenderViewHostChanged(content::RenderViewHost* old_host,
                                     content::RenderViewHost* new_host) {
   content::RenderWidgetHostView* view = new_host->GetWidget()->GetView();
   view->SetBackgroundColor(SK_ColorTRANSPARENT);
   view->SetIsInVR(true);
 }
 
 void VrShell::MainFrameWasResized(bool width_changed) {
   display::Display display =
       display::Screen::GetScreen()->GetDisplayNearestView(
@@ skipping 227 matching lines @@
            jboolean reprojected_rendering) {
   return reinterpret_cast<intptr_t>(new VrShell(
       env, obj, reinterpret_cast<ui::WindowAndroid*>(content_window_android),
       content::WebContents::FromJavaWebContents(ui_web_contents),
       reinterpret_cast<ui::WindowAndroid*>(ui_window_android), for_web_vr,
       VrShellDelegate::GetNativeVrShellDelegate(env, delegate),
       reinterpret_cast<gvr_context*>(gvr_api), reprojected_rendering));
 }
 
 }  // namespace vr_shell