[sensors] Add Permission guard to the generic sensor apis.

third_party/WebKit/Source/modules/sensor/SensorProxy.cpp

 // 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 "modules/sensor/SensorProxy.h"
 
 #include "core/frame/LocalFrame.h"
+#include "modules/permissions/PermissionUtils.h"
 #include "modules/sensor/SensorProviderProxy.h"
 #include "modules/sensor/SensorReading.h"
+#include "platform/UserGestureIndicator.h"
 #include "platform/mojo/MojoHelper.h"
+#include "platform/weborigin/SecurityOrigin.h"
 #include "public/platform/Platform.h"
 
 using namespace device::mojom::blink;
 
 namespace blink {
 
+using mojom::blink::PermissionName;
+using mojom::blink::PermissionService;
+using mojom::blink::PermissionStatus;
+
 SensorProxy::SensorProxy(SensorType sensorType,
+                         PermissionService* permissionService,
+                         RefPtr<SecurityOrigin> origin,
                          SensorProviderProxy* provider,
                          std::unique_ptr<SensorReadingFactory> readingFactory)
     : m_type(sensorType),
       m_mode(ReportingMode::CONTINUOUS),
       m_provider(provider),
       m_clientBinding(this),
       m_state(SensorProxy::Uninitialized),
       m_suspended(false),
       m_readingFactory(std::move(readingFactory)),
-      m_maximumFrequency(0.0) {}
+      m_maximumFrequency(0.0),
+      m_permissionStatus(PermissionStatus::ASK),
+      m_permissionService(permissionService),
+      m_securityOrigin(std::move(origin)) {}
+
+void SensorProxy::onPermissionUpdate(PermissionStatus status) {
+  if (m_state == Uninitialized)
+    return;
+
+  if (m_permissionStatus != status)
+    m_permissionStatus = status;

[Mikhail, 2016/11/22 21:24:41]

looks like 'm_permissionStatus' is not needed and can be removed from the class.

[riju_, 2016/11/23 09:02:28]

I would like to be always sure that SensorProxy starts with
PermissionStatus::ASK.

+
+  // If permission is revoked, throw error.
+  if (m_permissionStatus != PermissionStatus::GRANTED) {

[Mikhail, 2016/11/22 21:24:40]

can it be ASK again?

[Mikhail, 2016/11/22 21:24:41]

== Denied

[riju_, 2016/11/23 09:02:28]

Acknowledged.

[riju_, 2016/11/23 09:02:28]

Acknowledged.

+    handleSensorError(NotAllowedError, "Permission not granted.");

[Mikhail, 2016/11/22 21:24:41]

return here (no need to subscribe for further notification)

[riju_, 2016/11/23 09:02:29]

Acknowledged.

+  } else {
+    if (isInitializing()) {
+      m_state = Initialized;
+      for (Observer* observer : m_observers)
+        observer->onSensorInitialized();
+    }
+  }
+
+  // Keep listening to changes.
+  m_permissionService->GetNextPermissionChange(

[Mikhail, 2016/11/22 21:24:41]

can we drop this subscription at 'handleSensorError'?

[riju_, 2016/11/23 09:02:28]

resetPermissionService() will now be called if DENIED, which will reset all
callbacks on the permissionService interfacePtr

+      createPermissionDescriptor(PermissionName::SENSORS), m_securityOrigin,
+      m_permissionStatus,
+      convertToBaseCallback(WTF::bind(&SensorProxy::onPermissionUpdate,
+                                      wrapWeakPersistent(this))));
+}
 
 SensorProxy::~SensorProxy() {}
 
 void SensorProxy::dispose() {
   m_clientBinding.Close();
 }
 
 DEFINE_TRACE(SensorProxy) {
   visitor->trace(m_reading);
   visitor->trace(m_observers);
@@ skipping 145 matching lines @@
 
   m_maximumFrequency = params->maximum_frequency;
   DCHECK(m_maximumFrequency <= SensorConfiguration::kMaxAllowedFrequency);
 
   auto errorCallback =
       WTF::bind(&SensorProxy::handleSensorError, wrapWeakPersistent(this),
                 UnknownError, String("Internal error"), String());
   m_sensor.set_connection_error_handler(
       convertToBaseCallback(std::move(errorCallback)));
 
-  m_state = Initialized;
-  for (Observer* observer : m_observers)
-    observer->onSensorInitialized();
+  // Request permission.
+  m_permissionService->RequestPermission(
+      createPermissionDescriptor(PermissionName::SENSORS), m_securityOrigin,
+      UserGestureIndicator::processingUserGesture(),
+      convertToBaseCallback(WTF::bind(&SensorProxy::onPermissionUpdate,
+                                      wrapWeakPersistent(this))));
 }
 
 bool SensorProxy::tryReadFromBuffer(device::SensorReading& result) {
   DCHECK(isInitialized());
   const ReadingBuffer* buffer =
       static_cast<const ReadingBuffer*>(m_sharedBuffer.get());
   const device::OneWriterSeqLock& seqlock = buffer->seqlock.value();
   auto version = seqlock.ReadBegin();
   auto readingData = buffer->reading;
   if (seqlock.ReadRetry(version))
     return false;
   result = readingData;
   return true;
 }
 
 }  // namespace blink