Fix assertion starting cast_shell (breaking thread IO restrictions).

ui/events/ozone/device/device_manager_manual.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 "ui/events/ozone/device/device_manager_manual.h"
 
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/files/file_enumerator.h"
+#include "base/location.h"
+#include "base/threading/worker_pool.h"
 #include "ui/events/ozone/device/device_event.h"
 #include "ui/events/ozone/device/device_event_observer.h"
 
 namespace ui {
 
-DeviceManagerManual::DeviceManagerManual() {}
+namespace {
 
-DeviceManagerManual::~DeviceManagerManual() {}
-
-void DeviceManagerManual::ScanDevices(DeviceEventObserver* observer) {
+void ScanDevicesOnWorkerThread(std::vector<base::FilePath>* result) {
   base::FileEnumerator file_enum(base::FilePath("/dev/input"),
                                  false,
                                  base::FileEnumerator::FILES,
                                  "event*[0-9]");
   for (base::FilePath path = file_enum.Next(); !path.empty();
        path = file_enum.Next()) {
-    DeviceEvent event(DeviceEvent::INPUT, DeviceEvent::ADD, path);
-    observer->OnDeviceEvent(event);
+    result->push_back(path);
   }
 }
 
-void DeviceManagerManual::AddObserver(DeviceEventObserver* observer) {}
+}
 
-void DeviceManagerManual::RemoveObserver(DeviceEventObserver* observer) {}
+DeviceManagerManual::DeviceManagerManual()
+    : have_scanned_devices_(false)
+    , weak_ptr_factory_(this) {

[spang, 2015/01/22 20:45:57]

whitespace issue, please git cl format.

[halliwell, 2015/01/22 21:56:52]

Done.

+}
+
+DeviceManagerManual::~DeviceManagerManual() {}
+
+void DeviceManagerManual::ScanDevices(DeviceEventObserver* observer) {
+  if (have_scanned_devices_) {
+    std::vector<base::FilePath>::const_iterator it = devices_.begin();
+    for (; it != devices_.end(); ++it) {
+      DeviceEvent event(DeviceEvent::INPUT, DeviceEvent::ADD, *it);
+      observer->OnDeviceEvent(event);
+    }
+  } else {
+    std::vector<base::FilePath>* result = new std::vector<base::FilePath>();
+    base::WorkerPool::PostTaskAndReply(
+        FROM_HERE,
+        base::Bind(&ScanDevicesOnWorkerThread, result),
+        base::Bind(&DeviceManagerManual::OnDevicesScanned,
+                   weak_ptr_factory_.GetWeakPtr(),
+                   base::Owned(result)),
+        true /* task_is_slow */);

[jochen (gone - plz use gerrit), 2015/01/22 16:28:15]

not sure this is a slow task - this will start a new dedicated thread (which is
a good idea for something running something like a minute or longer, but
otherwise not required)

[halliwell, 2015/01/22 21:56:52]

Done.

+    have_scanned_devices_ = true;
+  }
+}
+
+void DeviceManagerManual::AddObserver(DeviceEventObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void DeviceManagerManual::RemoveObserver(DeviceEventObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void DeviceManagerManual::OnDevicesScanned(
+    std::vector<base::FilePath>* result) {
+  std::vector<base::FilePath>::const_iterator it = result->begin();
+  for (; it != result->end(); ++it) {
+    devices_.push_back(*it);
+    DeviceEvent event(DeviceEvent::INPUT, DeviceEvent::ADD, *it);
+    FOR_EACH_OBSERVER(
+        DeviceEventObserver, observers_, OnDeviceEvent(event));
+  }
+}
 
 }  // namespace ui