Make deviceorientationabsolute confrom with spec on Chromium OS

content/browser/device_sensors/data_fetcher_shared_memory_chromeos.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/device_sensors/data_fetcher_shared_memory.h"
 
 #include "content/browser/device_sensors/sensor_manager_chromeos.h"
 
 namespace content {
 
@@ skipping 10 matching lines @@
 
   switch (consumer_type) {
     case CONSUMER_TYPE_MOTION:
       sensor_manager_->StartFetchingDeviceMotionData(
           static_cast<DeviceMotionHardwareBuffer*>(buffer));
       return true;
     case CONSUMER_TYPE_ORIENTATION:
       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;
   }
   NOTREACHED();
   return false;
 }
 
 bool DataFetcherSharedMemory::Stop(ConsumerType consumer_type) {
   switch (consumer_type) {
     case CONSUMER_TYPE_MOTION:
       return sensor_manager_->StopFetchingDeviceMotionData();
     case CONSUMER_TYPE_ORIENTATION:
       return sensor_manager_->StopFetchingDeviceOrientationData();
     case CONSUMER_TYPE_ORIENTATION_ABSOLUTE:

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

best to have some 'clean-up' code here as well

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

Good call. Done.

     case CONSUMER_TYPE_LIGHT:
       NOTIMPLEMENTED();
       return false;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace content