Make deviceorientationabsolute confrom with spec on Chromium OS

content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc

Index: content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc
diff --git a/content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc b/content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc
index 16abd5ebf8a96847e5f6e63ce601bcb41335b50b..01813ffabb078a14bc7a5e5d96844bb34988650c 100644
--- a/content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc
+++ b/content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc
@@ -28,7 +28,16 @@ bool DataFetcherSharedMemory::Start(ConsumerType consumer_type, void* buffer) {
       sensor_manager_->StartFetchingDeviceOrientationData(
           static_cast<DeviceOrientationHardwareBuffer*>(buffer));
       return true;
-    case CONSUMER_TYPE_ORIENTATION_ABSOLUTE:
+    case CONSUMER_TYPE_ORIENTATION_ABSOLUTE: {
+      DeviceOrientationHardwareBuffer* orientation_absolute_buffer =
+          static_cast<DeviceOrientationHardwareBuffer*>(buffer);
+      // Absolute device orientation not available on Chrome OS, let the
+      // implementation fire an all-null event to signal this to blink.
+      orientation_absolute_buffer->seqlock.WriteBegin();

[timvolodine, 2016/05/06 15:10:41]

think it would be good to also set data.absolute = true here, that way
implementation would explicitly know what kind of event it is, plus also more in
line with the spec.

[jonross, 2016/05/06 17:57:43]

Done.

+      orientation_absolute_buffer->data.allAvailableSensorsAreActive = true;
+      orientation_absolute_buffer->seqlock.WriteEnd();
+      return false;
+    }
     case CONSUMER_TYPE_LIGHT:
       NOTIMPLEMENTED();
       return false;