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

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

Index: third_party/WebKit/Source/modules/sensor/Sensor.cpp
diff --git a/third_party/WebKit/Source/modules/sensor/Sensor.cpp b/third_party/WebKit/Source/modules/sensor/Sensor.cpp
index 0a0ded64b3d126ed3e66cfde7491dc0d3b350ee7..5b6fe150d49867a0c44f2d40ed80f0fbcac022a2 100644
--- a/third_party/WebKit/Source/modules/sensor/Sensor.cpp
+++ b/third_party/WebKit/Source/modules/sensor/Sensor.cpp
@@ -13,6 +13,7 @@
 #include "modules/sensor/SensorPollingStrategy.h"
 #include "modules/sensor/SensorProviderProxy.h"
 #include "modules/sensor/SensorReading.h"
+#include "platform/UserGestureIndicator.h"
 
 using namespace device::mojom::blink;
 
@@ -72,6 +73,14 @@ void Sensor::start(ScriptState* scriptState, ExceptionState& exceptionState) {
     return;
   }
 
+  // If the algorithm is not allowed to show a popup, throw SecurityError.
+  if (!UserGestureIndicator::consumeUserGesture()) {

[shalamov, 2016/11/16 11:10:22]

I have two comments for this line:

1. Since it does not need anything from the sensor, it can be moved to the proxy
where all permissions are handled now.

2. Why is this needed?

[riju_, 2016/11/16 12:38:25]

I am removing it now, as getting "sensor" information might not qualify as very
security-sensitive, as defined in
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/platform/UserG...

Let's check if this is required with the security-folks. If needed, I will add
this back to SensorProxy.

+    exceptionState.throwDOMException(
+        SecurityError,
+        "Must be handling a user gesture to show a permission request.");
+    return;
+  }
+
   initSensorProxyIfNeeded();
 
   if (!m_sensorProxy) {
@@ -167,8 +176,8 @@ void Sensor::initSensorProxyIfNeeded() {
   m_sensorProxy = provider->getSensor(m_type);
 
   if (!m_sensorProxy) {
-    m_sensorProxy =
-        provider->createSensor(m_type, createSensorReadingFactory());
+    m_sensorProxy = provider->createSensor(m_type, getExecutionContext(),
+                                           createSensorReadingFactory());
   }
 }