Isolate a presenting VR device from pages other than the one presenting.

device/vr/vr_device_manager.cc

 // Copyright 2015 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 "device/vr/vr_device_manager.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "build/build_config.h"
 
 #if defined(OS_ANDROID)
 #include "device/vr/android/gvr/gvr_device_provider.h"
 #endif
 
 namespace device {
 
 namespace {
 VRDeviceManager* g_vr_device_manager = nullptr;
 }
 
 VRDeviceManager::VRDeviceManager()
-    : vr_initialized_(false), keep_alive_(false), has_scheduled_poll_(false) {
+    : vr_initialized_(false),
+      presenting_service_(nullptr),
+      presenting_device_(nullptr),
+      keep_alive_(false),
+      has_scheduled_poll_(false) {
 // Register VRDeviceProviders for the current platform
 #if defined(OS_ANDROID)
   RegisterProvider(base::WrapUnique(new GvrDeviceProvider()));
 #endif
 }
 
 VRDeviceManager::VRDeviceManager(std::unique_ptr<VRDeviceProvider> provider)
-    : vr_initialized_(false), keep_alive_(true), has_scheduled_poll_(false) {
+    : vr_initialized_(false),
+      presenting_service_(nullptr),
+      presenting_device_(nullptr),
+      keep_alive_(true),
+      has_scheduled_poll_(false) {
   thread_checker_.DetachFromThread();
   RegisterProvider(std::move(provider));
   SetInstance(this);
 }
 
 VRDeviceManager::~VRDeviceManager() {
   DCHECK(thread_checker_.CalledOnValidThread());
   StopSchedulingPollEvents();
   g_vr_device_manager = nullptr;
 }
 
 VRDeviceManager* VRDeviceManager::GetInstance() {
   if (!g_vr_device_manager)
     g_vr_device_manager = new VRDeviceManager();
   return g_vr_device_manager;
 }
 
+// Returns the requested device with the requested id if the specified service
+// is allowed to access it.
+VRDevice* VRDeviceManager::GetAllowedDevice(VRServiceImpl* service,
+                                            unsigned int index) {
+  VRDeviceManager* device_manager = GetInstance();
+
+  // If another service is presenting to the requested device don't allow other
+  // services to access it. That could potentially allow them to spy on
+  // where the user is looking on another page, spam another application with
+  // pose resets, etc.
+  if (device_manager->presenting_service_ &&
+      device_manager->presenting_service_ != service) {
+    if (device_manager->presenting_device_ &&
+        device_manager->presenting_device_->id() == index)
+      return nullptr;
+  }
+
+  return device_manager->GetDevice(index);
+}
+
 void VRDeviceManager::SetInstance(VRDeviceManager* instance) {
   // Unit tests can create multiple instances but only one should exist at any
   // given time so g_vr_device_manager should only go from nullptr to
   // non-nullptr and vica versa.
   CHECK_NE(!!instance, !!g_vr_device_manager);
   g_vr_device_manager = instance;
 }
 
 bool VRDeviceManager::HasInstance() {
   // For testing. Checks to see if a VRDeviceManager instance is active.
   return !!g_vr_device_manager;
 }
 
 void VRDeviceManager::AddService(VRServiceImpl* service) {
   services_.push_back(service);
 
   // Ensure that the device providers are initialized
   InitializeProviders();
 }
 
 void VRDeviceManager::RemoveService(VRServiceImpl* service) {
   services_.erase(std::remove(services_.begin(), services_.end(), service),
                   services_.end());
 
+  if (service == presenting_service_) {
+    presenting_device_->ExitPresent();
+
+    presenting_service_ = nullptr;
+    presenting_device_ = nullptr;
+  }
+
   if (services_.empty() && !keep_alive_) {
     // Delete the device manager when it has no active connections.
     delete g_vr_device_manager;
   }
 }
 
 mojo::Array<VRDisplayPtr> VRDeviceManager::GetVRDevices() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   InitializeProviders();
@@ skipping 35 matching lines @@
   return iter->second;
 }
 
 // These dispatchers must use Clone() instead of std::move to ensure that
 // if there are multiple registered services they all get a copy of the data.
 void VRDeviceManager::OnDeviceChanged(VRDisplayPtr device) {
   for (const auto& service : services_)
     service->client()->OnDisplayChanged(device.Clone());
 }
 
+bool VRDeviceManager::RequestPresent(VRServiceImpl* service,
+                                     unsigned int index) {
+  // Is anything presenting currently?
+  if (presenting_service_) {
+    // Should never have a presenting service without a presenting device.
+    DCHECK(presenting_device_);
+
+    // Fail if the currently presenting service is not the one making the
+    // request.
+    if (presenting_service_ != service)
+      return false;
+
+    // If we are switching presentation from the currently presenting service to
+    // a new device stop presening to the previous one.
+    if (presenting_device_->id() != index) {
+      // Tell the device to stop presenting.
+      presenting_device_->ExitPresent();
+
+      // Only the presenting service needs to be notified that presentation is
+      // ending on the previous device.
+      presenting_service_->client()->OnExitPresent(presenting_device_->id());
+      presenting_device_ = nullptr;
+    }
+
+    presenting_service_ = nullptr;
+  }
+
+  VRDevice* requested_device = GetDevice(index);
+  // Can't present to a device that doesn't exist.
+  if (!requested_device)
+    return false;
+
+  // Attempt to begin presenting to this device. This could fail for any number
+  // of device-specific reasons.
+  if (!requested_device->RequestPresent())
+    return false;
+
+  // Successfully began presenting!
+  presenting_service_ = service;
+  presenting_device_ = requested_device;
+
+  return true;
+}
+
+void VRDeviceManager::ExitPresent(VRServiceImpl* service, unsigned int index) {
+  // Don't allow services other than the currently presenting one to exit
+  // presentation.
+  if (presenting_service_ != service)
+    return;
+
+  // Should never have a presenting service without a presenting device.
+  DCHECK(presenting_device_);
+
+  // Fail if the specified device is not currently presenting.
+  if (presenting_device_->id() != index)
+    return;
+
+  // Tell the device to stop presenting.
+  presenting_device_->ExitPresent();
+  presenting_service_->client()->OnExitPresent(index);
+
+  // Clear the presenting service and device.
+  presenting_service_ = nullptr;
+  presenting_device_ = nullptr;
+}
+
+void VRDeviceManager::SubmitFrame(VRServiceImpl* service,
+                                  unsigned int index,
+                                  VRPosePtr pose) {
+  // Don't allow services other than the currently presenting one to submit any
+  // frames.
+  if (presenting_service_ != service)
+    return;
+
+  // Should never have a presenting service without a presenting device.
+  DCHECK(presenting_device_);
+
+  // Don't submit frames to devices other than the currently presenting one.
+  if (presenting_device_->id() != index)
+    return;
+
+  presenting_device_->SubmitFrame(std::move(pose));
+}
+
 void VRDeviceManager::InitializeProviders() {
   if (vr_initialized_) {
     return;
   }
 
   for (const auto& provider : providers_)
     provider->Initialize();
 
   vr_initialized_ = true;
 }
@@ skipping 17 matching lines @@
   for (const auto& provider : providers_)
     provider->PollEvents();
 }
 
 void VRDeviceManager::StopSchedulingPollEvents() {
   if (has_scheduled_poll_)
     timer_.Stop();
 }
 
 }  // namespace device