Mac: fix Device Orientation absolute property and handle the no-sensor case.

content/browser/device_orientation/data_fetcher_shared_memory_mac.cc

 // Copyright 2013 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 "data_fetcher_shared_memory.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "third_party/sudden_motion_sensor/sudden_motion_sensor_mac.h"
 
@@ skipping 46 matching lines @@
   // After that the rest is just a bit of trigonometry.
   //
   // Also note that alpha can't be provided but it's assumed to be always zero.
   // This is necessary in order to provide enough information to solve
   // the equations.
   //
   const double kRad2deg = 180.0 / M_PI;
   double beta = kRad2deg * atan2(-axis_value[1], axis_value[2]);
   double gamma = kRad2deg * asin(axis_value[0]);
 
-  // TODO(aousterh): should absolute_ be set to false here?
-  // See crbug.com/136010.
-
   // Make sure that the interval boundaries comply with the specification. At
   // this point, beta is [-180, 180] and gamma is [-90, 90], but the spec has
   // the upper bound open on both.
   if (beta == 180.0)
     beta = -180;  // -180 == 180 (upside-down)
   if (gamma == 90.0)
     gamma = nextafter(90, 0);
 
   // At this point, DCHECKing is paranoia. Never hurts.
   DCHECK_GE(beta, -180.0);
@@ skipping 33 matching lines @@
 }
 
 DataFetcherSharedMemory::FetcherType DataFetcherSharedMemory::GetType() const {
   return FETCHER_TYPE_POLLING_CALLBACK;
 }
 
 bool DataFetcherSharedMemory::Start(ConsumerType consumer_type, void* buffer) {
   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
   DCHECK(buffer);
 
+  if (!sudden_motion_sensor_)
+    sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
+  bool sudden_motion_sensor_available = sudden_motion_sensor_.get() != NULL;
+
   switch (consumer_type) {
     case CONSUMER_TYPE_MOTION:
       motion_buffer_ = static_cast<DeviceMotionHardwareBuffer*>(buffer);
-      if (!sudden_motion_sensor_)
-        sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
       UMA_HISTOGRAM_BOOLEAN("InertialSensor.MotionMacAvailable",
-          sudden_motion_sensor_.get() != NULL);
-      return sudden_motion_sensor_.get() != NULL;
+          sudden_motion_sensor_available);
+      if (!sudden_motion_sensor_available) {
+        // No motion sensor available, fire an all-null event.
+        motion_buffer_->seqlock.WriteBegin();
+        motion_buffer_->data.allAvailableSensorsAreActive = true;
+        motion_buffer_->seqlock.WriteEnd();
+      }
+      return sudden_motion_sensor_available;
     case CONSUMER_TYPE_ORIENTATION:
       orientation_buffer_ =
           static_cast<DeviceOrientationHardwareBuffer*>(buffer);
-      if (!sudden_motion_sensor_)
-        sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
       UMA_HISTOGRAM_BOOLEAN("InertialSensor.OrientationMacAvailable",
-          sudden_motion_sensor_.get() != NULL);
-      return sudden_motion_sensor_.get() != NULL;
+          sudden_motion_sensor_available);
+      if (sudden_motion_sensor_available) {
+        // On Mac we cannot provide absolute orientation.
+        orientation_buffer_->seqlock.WriteBegin();
+        orientation_buffer_->data.absolute = false;
+        orientation_buffer_->data.hasAbsolute = true;
+        orientation_buffer_->seqlock.WriteEnd();
+      } else {
+        // No motion sensor available, fire an all-null event.
+        orientation_buffer_->seqlock.WriteBegin();
+        orientation_buffer_->data.allAvailableSensorsAreActive = true;
+        orientation_buffer_->seqlock.WriteEnd();
+      }
+      return sudden_motion_sensor_available;
     default:
       NOTREACHED();
   }
   return false;
 }
 
 bool DataFetcherSharedMemory::Stop(ConsumerType consumer_type) {
   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 
   switch (consumer_type) {
@@ skipping 13 matching lines @@
         orientation_buffer_ = NULL;
       }
       return true;
     default:
       NOTREACHED();
   }
   return false;
 }
 
 }  // namespace content