Tentatively goes into WebVR presentation mode if page listens to vrdisplayactivate.

chrome/browser/android/vr_shell/vr_shell_delegate.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_delegate.h"
 
 #include <utility>
 
 #include "base/android/jni_android.h"
 #include "base/callback_helpers.h"
 #include "chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h"
 #include "device/vr/android/gvr/gvr_delegate.h"
 #include "device/vr/android/gvr/gvr_device.h"
 #include "device/vr/android/gvr/gvr_device_provider.h"
 #include "jni/VrShellDelegate_jni.h"
 
 using base::android::JavaParamRef;
 using base::android::AttachCurrentThread;
 
 namespace vr_shell {
 
-VrShellDelegate::VrShellDelegate(JNIEnv* env, jobject obj) {
+VrShellDelegate::VrShellDelegate(JNIEnv* env, jobject obj)
+    : weak_ptr_factory_(this) {
   DVLOG(1) << __FUNCTION__ << "=" << this;
   j_vr_shell_delegate_.Reset(env, obj);
 }
 
 VrShellDelegate::~VrShellDelegate() {
   DVLOG(1) << __FUNCTION__ << "=" << this;
   if (device_provider_) {
     device_provider_->Device()->OnExitPresent();
     device_provider_->Device()->OnDelegateChanged();
   }
@@ skipping 67 matching lines @@
   }
 
   base::ResetAndReturn(&present_callback_).Run(success);
   pending_successful_present_request_ = false;
 }
 
 void VrShellDelegate::DisplayActivate(JNIEnv* env,
                                       const JavaParamRef<jobject>& obj) {
   if (device_provider_) {
     device_provider_->Device()->OnActivate(
-        device::mojom::VRDisplayEventReason::MOUNTED);
+        device::mojom::VRDisplayEventReason::MOUNTED,
+        base::Bind(&VrShellDelegate::OnActivateDisplayHandled,
+                   weak_ptr_factory_.GetWeakPtr()));
   }
 }
 
 void VrShellDelegate::UpdateVSyncInterval(JNIEnv* env,
                                           const JavaParamRef<jobject>& obj,
                                           jlong timebase_nanos,
                                           jdouble interval_seconds) {
   timebase_nanos_ = timebase_nanos;
   interval_seconds_ = interval_seconds;
   if (presenting_delegate_) {
@@ skipping 75 matching lines @@
   JNIEnv* env = AttachCurrentThread();
   gvr_context* context = reinterpret_cast<gvr_context*>(
       Java_VrShellDelegate_createNonPresentingNativeContext(
           env, j_vr_shell_delegate_.obj()));
   non_presenting_delegate_ =
       base::MakeUnique<NonPresentingGvrDelegate>(context);
   non_presenting_delegate_->UpdateVSyncInterval(timebase_nanos_,
                                                 interval_seconds_);
 }
 
+void VrShellDelegate::OnActivateDisplayHandled(bool present_requested) {
+  if (!present_requested) {
+    // WebVR page didn't request presentation in the vrdisplayactivate handler.
+    // Tell VrShell that we are in VR Browsing Mode.
+    ExitWebVRPresent();
+  }
+}
+
 device::GvrDelegate* VrShellDelegate::GetDelegate() {
   if (presenting_delegate_)
     return presenting_delegate_;
   return non_presenting_delegate_.get();
 }
 
 void VrShellDelegate::SetListeningForActivate(bool listening) {
   JNIEnv* env = AttachCurrentThread();
   Java_VrShellDelegate_setListeningForWebVrActivate(
       env, j_vr_shell_delegate_.obj(), listening);
@@ skipping 10 matching lines @@
 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