[Sensors] Improvements in shared buffer managing

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 be7150150a4f1a947941a0334358384508e09cd8..dbdccac83eb1272e75df20432a953e3ba4d4bf19 100644
--- a/device/generic_sensor/public/interfaces/sensor.mojom
+++ b/device/generic_sensor/public/interfaces/sensor.mojom
@@ -38,6 +38,16 @@ struct SensorConfiguration {
   // TODO(shalamov): Add map<string, union> for sensor specific configuration.
 };
 
+// Each sensor uses the following structure to provide reading data.
+struct SensorReading {
+  // Timestamp in seconds, obtained from system performance counter.
+  double timestamp;
+  // Sensor data fields.
+  double value1;
+  double value2;
+  double value3;
+};
+
 // Interface for controlling the Sensor.
 interface Sensor {