[Sensors] Allow Sensor API only on secure top-level browsing contexts and add frequency checks

device/generic_sensor/public/interfaces/sensor.mojom

Index: device/generic_sensor/public/interfaces/sensor.mojom
diff --git a/device/generic_sensor/public/interfaces/sensor.mojom b/device/generic_sensor/public/interfaces/sensor.mojom
index 74f57d480d5b335d9b9ee9271c807804e08858fd..be7150150a4f1a947941a0334358384508e09cd8 100644
--- a/device/generic_sensor/public/interfaces/sensor.mojom
+++ b/device/generic_sensor/public/interfaces/sensor.mojom
@@ -30,7 +30,10 @@ enum ReportingMode {
 };
 
 struct SensorConfiguration {
-  // Requested frequency in Hz (max is 60 Hz).
+  // Maximum allowed frequency is 60 Hz.
+  const double kMaxAllowedFrequency = 60.0;

[Tom Sepez, 2016/09/20 16:41:06]

nit: If we named this kMaxAllowedFrequencyHz, we could lose the comment entirel.

+
+  // Requested frequency in Hz.
   double frequency;
   // TODO(shalamov): Add map<string, union> for sensor specific configuration.
 };