[Sensors] Improvements in shared buffer managing

third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js

 'use strict';
 
 function sensor_mocks(mojo) {
   return define('Generic Sensor API mocks', [
     'mojo/public/js/core',
     'mojo/public/js/bindings',
     'mojo/public/js/connection',
     'device/generic_sensor/public/interfaces/sensor_provider.mojom',
     'device/generic_sensor/public/interfaces/sensor.mojom',
   ], (core, bindings, connection, sensor_provider, sensor) => {
@@ skipping 157 matching lines @@
 
     // Helper function that returns resolved promise for getSensor() function.
     function getSensorResponse(init_params, client_request) {
       return Promise.resolve({init_params, client_request});
     }
 
     // Class that mocks SensorProvider interface defined in
     // sensor_provider.mojom
     class MockSensorProvider {
       constructor() {
-        this.reading_size_in_bytes_ =
-            sensor_provider.SensorInitParams.kReadBufferSize;
+        this.reading_size_in_bytes_ = 40; // sizeof(device::SharedMemorySeqLockBuffer<device::mojom::blink::SensorReading>).

[shalamov, 2016/10/06 12:46:09]

this.reading_size_in_bytes_ = (Object.keys(new sensor.SensorReading()).length +
1) * Float64Array.BYTES_PER_ELEMENT;

Object.keys(new sensor.SensorReading()).length - SensorReading field count
+ 1 // seq lock
Float64Array.BYTES_PER_ELEMENT // num of bytes per field

         this.shared_buffer_size_in_bytes_ = this.reading_size_in_bytes_ *
                 sensor.SensorType.LAST;
         let rv =
                 core.createSharedBuffer(
                         this.shared_buffer_size_in_bytes_,
                         core.CREATE_SHARED_BUFFER_OPTIONS_FLAG_NONE);
         assert_equals(rv.result, core.RESULT_OK, "Failed to create buffer");
         this.shared_buffer_handle_ = rv.handle;
         this.active_sensor_ = null;
         this.get_sensor_should_fail_ = false;
@@ skipping 103 matching lines @@
   });
 }
 
 function sensor_test(func, name, properties) {
   mojo_test(mojo => sensor_mocks(mojo).then(sensor => {
     let result = Promise.resolve(func(sensor));
     let cleanUp = () => { sensor.mockSensorProvider.reset(); };
     return result.then(cleanUp, cleanUp);
   }), name, properties);
 }