[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,
                          Page* page,
                          std::unique_ptr<SensorReadingFactory> readingFactory)
     : PageVisibilityObserver(page),
       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_timer(this, &SensorProxy::onTimerFired) {}
+      m_timer(this, &SensorProxy::onTimerFired),
+      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, 2016/11/28 20:07:53]

Think m_permissionStatus is not needed as not used outside of this method, and
inside as well :) (didn't I leave this comment already?)

[riju_, 2016/11/29 07:19:47]

Because I wanted to make sure that, whenever SensorProxy is created, it is
always initialized to ASK.

[shalamov, 2016/11/29 08:29:10]

I agree with Mikhail, this line of code and member variable doesn't do anything
and can be removed.

[Mikhail, 2016/11/29 08:46:29]

mm.. how does it help to make sure it is always initialized to ASK?

+
+  switch (status) {
+    case mojom::blink::PermissionStatus::DENIED:
+      handleSensorError(NotAllowedError, "Permission denied.");
+      return;
+    case mojom::blink::PermissionStatus::ASK:
+      handleSensorError(NotAllowedError, "Permission revoked.");
+      break;

[Mikhail, 2016/11/28 20:07:53]

why not return here?

[riju_, 2016/11/29 07:19:47]

Because if it is ASK, I would still like to subscribe to
GetNextPermissionChange. 
ASK->GRANTED is a valid change. Only when its DENIED, there is no need to
subscribe to further changes.

[Mikhail, 2016/11/29 08:46:29]

This subscription is meaningless as error handler will put proxy to
"uninitialized" state, which cause early return from this method, or am I
missing something?

+    case mojom::blink::PermissionStatus::GRANTED:
+      if (isInitializing()) {
+        m_state = Initialized;
+        for (Observer* observer : m_observers)
+          observer->onSensorInitialized();
+      }
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  // Keep listening to changes.
+  m_permissionService->GetNextPermissionChange(
+      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 179 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))));
 }
 
 void SensorProxy::onAddConfigurationCompleted(
     double frequency,
     std::unique_ptr<Function<void(bool)>> callback,
     bool result) {
   if (usesPollingTimer() && result) {
     m_frequenciesUsed.append(frequency);
     updatePollingStatus();
   }
@@ skipping 50 matching lines @@
     updateSensorReading();
     m_timer.startRepeating(repeatInterval, BLINK_FROM_HERE);
   }
 }
 
 void SensorProxy::onTimerFired(TimerBase*) {
   updateSensorReading();
 }
 
 }  // namespace blink