[Sensors] Improvements in shared buffer managing

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

Index: third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
diff --git a/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js b/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
index f9099600d5c9fe7b12d6b614d82d9cff3ef2d33b..4ae33d137fb57345f92f9f5d787bb4dae5f6b74b 100644
--- a/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
+++ b/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
@@ -175,8 +175,7 @@ function sensor_mocks(mojo) {
     // 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 =