[Sensors] Improvements in shared buffer managing

third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html

Index: third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html
diff --git a/third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html b/third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html
index 453a5ad136b5ebe85650d966565dbb902e984bf5..30fbad677023864c861dc0f6abc128755e2bec8d 100644
--- a/third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html
+++ b/third_party/WebKit/LayoutTests/sensor/ambient-light-sensor.html
@@ -13,8 +13,9 @@ if (!window.testRunner)
 const kDefaultReadingValue = 3.1415;
 
 function update_sensor_reading(buffer) {
-  buffer[0] = window.performance.now();
-  buffer[1] = kDefaultReadingValue;
+  buffer[0] = 0.0; // Placeholder for seqlock.

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

Maybe better to make resetBuffer() function in sensor-helpers.js and then call
it after this.buffer_ = new Float64Array(this.buffer_array_);
and also reuse it in reset();

resetBuffer()
for (let i = 0; i < this.buffer_.length; ++i) {
          this.buffer_[i] = 0;
}
}

Then, you can remove buffer[0] = 0.0; // Placeholder for seqlock. and start
writing values starting from buffer[1]...

[Mikhail, 2016/10/07 10:07:02]

Done.

+  buffer[1] = window.performance.now();
+  buffer[2] = kDefaultReadingValue;
 }
 
 test(() => assert_throws(