Correcly Report CanEnterMaximizeMode on devices without accelerometers

chromeos/accelerometer/accelerometer_reader.cc

 // Copyright 2014 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 "chromeos/accelerometer/accelerometer_reader.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
@@ skipping 185 matching lines @@
   // startup.
   base::PostTaskAndReplyWithResult(
       task_runner_.get(), FROM_HERE,
       base::Bind(&DetectAndReadAccelerometerConfiguration, configuration_),
       base::Bind(&AccelerometerReader::OnInitialized,
                  weak_factory_.GetWeakPtr(), configuration_));
 }
 
 void AccelerometerReader::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
-  observer->OnAccelerometerUpdated(update_);
+  if (has_update_)
+    observer->OnAccelerometerUpdated(update_);
 }
 
 void AccelerometerReader::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 AccelerometerReader::AccelerometerReader()
-    : configuration_(new AccelerometerReader::Configuration()),
+    : has_update_(false),
+      configuration_(new AccelerometerReader::Configuration()),
       weak_factory_(this) {
 }
 
 AccelerometerReader::~AccelerometerReader() {
 }
 
 void AccelerometerReader::OnInitialized(
     scoped_refptr<AccelerometerReader::Configuration> configuration,
     bool success) {
   if (success)
@@ skipping 13 matching lines @@
                                               weak_factory_.GetWeakPtr(),
                                               reading));
 }
 
 void AccelerometerReader::OnDataRead(
     scoped_refptr<AccelerometerReader::Reading> reading,
     bool success) {
   DCHECK(!task_runner_->RunsTasksOnCurrentThread());
 
   if (success) {
+    has_update_ = true;
     for (int i = 0; i < ACCELEROMETER_SOURCE_COUNT; ++i) {
       if (!configuration_->data.has[i])
         continue;
 
       int16* values = reinterpret_cast<int16*>(reading->data);
       update_.Set(static_cast<AccelerometerSource>(i),
                   values[configuration_->data.index[i][0]] *
                       configuration_->data.scale[i][0],
                   values[configuration_->data.index[i][1]] *
                       configuration_->data.scale[i][1],
                   values[configuration_->data.index[i][2]] *
                       configuration_->data.scale[i][2]);
     }
     FOR_EACH_OBSERVER(Observer, observers_, OnAccelerometerUpdated(update_));
   }
 
   // Trigger another read after the current sampling delay.
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&AccelerometerReader::TriggerRead,
                  weak_factory_.GetWeakPtr()),
       base::TimeDelta::FromMilliseconds(kDelayBetweenReadsMs));
 }
 
 }  // namespace chromeos