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

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

Index: third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
diff --git a/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp b/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
index e3b01f30c0d560100a8eb40e5720b98fa23a2870..7620fd4400d47b3367f76bfdc92ca5f486327e86 100644
--- a/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
+++ b/third_party/WebKit/Source/modules/sensor/SensorProxy.cpp
@@ -5,16 +5,25 @@
 #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),
@@ -24,7 +33,32 @@ SensorProxy::SensorProxy(SensorType sensorType,
       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;
+    if (isInitializing())

[Mikhail, 2016/11/21 14:29:41]

what if this came after permission has already been obtained and we're in the
middle of GetSensor() call? it will be called another time, right?

and if the new value is ASK (and we're still initializing) it will ask for
permission again?

+      initialize();
+  }
+
+  // If permission is revoked, throw error.
+  if (isInitialized() && m_permissionStatus != PermissionStatus::GRANTED)
+    handleSensorError(NotAllowedError, "Permission not granted.");
+
+  // Keep listening to changes.
+  m_permissionService->GetNextPermissionChange(
+      createPermissionDescriptor(PermissionName::SENSORS), m_securityOrigin,
+      m_permissionStatus,
+      convertToBaseCallback(WTF::bind(&SensorProxy::onPermissionUpdate,
+                                      wrapWeakPersistent(this))));
+}
 
 SensorProxy::~SensorProxy() {}
 
@@ -48,7 +82,7 @@ void SensorProxy::removeObserver(Observer* observer) {
 }
 
 void SensorProxy::initialize() {
-  if (m_state != Uninitialized)
+  if (m_state == Initialized)
     return;
 
   if (!m_provider->sensorProvider()) {
@@ -57,10 +91,28 @@ void SensorProxy::initialize() {
   }
 
   m_state = Initializing;
-  auto callback = convertToBaseCallback(
-      WTF::bind(&SensorProxy::onSensorCreated, wrapWeakPersistent(this)));
-  m_provider->sensorProvider()->GetSensor(m_type, mojo::GetProxy(&m_sensor),
-                                          callback);
+
+  switch (m_permissionStatus) {
+    case PermissionStatus::ASK:
+      // Request permission.
+      m_permissionService->RequestPermission(
+          createPermissionDescriptor(PermissionName::SENSORS), m_securityOrigin,
+          UserGestureIndicator::processingUserGesture(),
+          convertToBaseCallback(WTF::bind(&SensorProxy::onPermissionUpdate,
+                                          wrapWeakPersistent(this))));
+      break;
+    case PermissionStatus::DENIED:
+      handleSensorError(NotAllowedError, "Permission not granted.");

[Mikhail, 2016/11/21 14:29:41]

so, state will be still "Initializing"?

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

handleSensorError resets m_state to Uninitialized.
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/sensor...

+      break;
+    case PermissionStatus::GRANTED:
+      m_provider->sensorProvider()->GetSensor(
+          m_type, mojo::GetProxy(&m_sensor),
+          convertToBaseCallback(WTF::bind(&SensorProxy::onSensorCreated,
+                                          wrapWeakPersistent(this))));
+      break;
+    default:
+      NOTREACHED();
+  }
 }
 
 void SensorProxy::addConfiguration(