[Sensors] Reland: Reland: Align sensor reading updates and 'onchange' notification with rAF.

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 262145feca1793baebf1d93189cdde29be69e497..236262f349f50d185ffa0fb3476e589cc635b794 100644
--- a/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
+++ b/third_party/WebKit/LayoutTests/sensor/resources/sensor-helpers.js
@@ -41,6 +41,7 @@ function sensor_mocks(mojo) {
         this.reporting_mode_ = reportingMode;
         this.sensor_reading_timer_id_ = null;
         this.update_reading_function_ = null;
+        this.reading_updates_count_ = 0;
         this.suspend_called_ = null;
         this.resume_called_ = null;
         this.add_configuration_called_ = null;
@@ -63,6 +64,9 @@ function sensor_mocks(mojo) {
         return Promise.resolve({frequency: 5});
       }
 
+      reading_updates_count() {
+        return this.reading_updates_count_;
+      }
       // Adds configuration for the sensor and starts reporting fake data
       // through update_reading_function_ callback.
       addConfiguration(configuration) {
@@ -127,6 +131,7 @@ function sensor_mocks(mojo) {
         this.stopReading();
 
         this.expects_modified_reading_ = false;
+        this.reading_updates_count_ = 0;
         this.start_should_fail_ = false;
         this.update_reading_function_ = null;
         this.active_sensor_configurations_ = [];
@@ -194,13 +199,17 @@ function sensor_mocks(mojo) {
 
       startReading() {
         if (this.update_reading_function_ != null) {
+          this.stopReading();
           let max_frequency_used =
               this.active_sensor_configurations_[0].frequency;
           let timeout = (1 / max_frequency_used) * 1000;
           this.sensor_reading_timer_id_ = window.setInterval(() => {
-            if (this.update_reading_function_)
+            if (this.update_reading_function_) {
               this.update_reading_function_(this.buffer_,
-                                            this.expects_modified_reading_);
+                                            this.expects_modified_reading_,
+                                            this.reading_updates_count_);
+              this.reading_updates_count_++;
+            }
             if (this.reporting_mode_ === sensor.ReportingMode.ON_CHANGE) {
               this.client_.sensorReadingChanged();
             }