Send WM_DEVICECHANGE message through SystemMonitor

WM_DEVICECHANGE is sent when there's been a change to devices or the computer;
specifically when a USB device is connected or disconnected. This is intended
for use in support of Gamepads for more performant polling and
connect/disconnect testing. Currently only on Windows, though seems reasonable
to add for other platforms in the future.

BUG=79050


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=109960

Review URL: http://codereview.chromium.org/8523021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110014 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 95 insertions, 12 deletions

diff --git a/base/system_monitor/system_monitor.cc b/base/system_monitor/system_monitor.cc
index 5131fbf..28fc70b 100644
--- a/base/system_monitor/system_monitor.cc
+++ b/base/system_monitor/system_monitor.cc
@@ -19,7 +19,9 @@ static int kDelayedBatteryCheckMs = 10 * 1000;
 #endif  // defined(ENABLE_BATTERY_MONITORING)
 
 SystemMonitor::SystemMonitor()
-    : observer_list_(new ObserverListThreadSafe<PowerObserver>()),
+    : power_observer_list_(new ObserverListThreadSafe<PowerObserver>()),
+      devices_changed_observer_list_(
+          new ObserverListThreadSafe<DevicesChangedObserver>()),
       battery_in_use_(false),
       suspended_(false) {
   DCHECK(!g_system_monitor);
@@ -77,28 +79,47 @@ void SystemMonitor::ProcessPowerMessage(PowerEvent event_id) {
   }
 }
 
-void SystemMonitor::AddObserver(PowerObserver* obs) {
-  observer_list_->AddObserver(obs);
+void SystemMonitor::ProcessDevicesChanged() {
+  NotifyDevicesChanged();
 }
 
-void SystemMonitor::RemoveObserver(PowerObserver* obs) {
-  observer_list_->RemoveObserver(obs);
+void SystemMonitor::AddPowerObserver(PowerObserver* obs) {
+  power_observer_list_->AddObserver(obs);
+}
+
+void SystemMonitor::RemovePowerObserver(PowerObserver* obs) {
+  power_observer_list_->RemoveObserver(obs);
+}
+
+void SystemMonitor::AddDevicesChangedObserver(DevicesChangedObserver* obs) {
+  devices_changed_observer_list_->AddObserver(obs);
+}
+
+void SystemMonitor::RemoveDevicesChangedObserver(DevicesChangedObserver* obs) {
+  devices_changed_observer_list_->RemoveObserver(obs);
+}
+
+void SystemMonitor::NotifyDevicesChanged() {
+  DVLOG(1) << "DevicesChanged";
+  devices_changed_observer_list_->Notify(
+    &DevicesChangedObserver::OnDevicesChanged);
 }
 
 void SystemMonitor::NotifyPowerStateChange() {
   DVLOG(1) << "PowerStateChange: " << (BatteryPower() ? "On" : "Off")
            << " battery";
-  observer_list_->Notify(&PowerObserver::OnPowerStateChange, BatteryPower());
+  power_observer_list_->Notify(&PowerObserver::OnPowerStateChange,
+                               BatteryPower());
 }
 
 void SystemMonitor::NotifySuspend() {
   DVLOG(1) << "Power Suspending";
-  observer_list_->Notify(&PowerObserver::OnSuspend);
+  power_observer_list_->Notify(&PowerObserver::OnSuspend);
 }
 
 void SystemMonitor::NotifyResume() {
   DVLOG(1) << "Power Resuming";
-  observer_list_->Notify(&PowerObserver::OnResume);
+  power_observer_list_->Notify(&PowerObserver::OnResume);
 }
 
 void SystemMonitor::BatteryCheck() {
diff --git a/base/system_monitor/system_monitor.h b/base/system_monitor/system_monitor.h
index c779994..7684523 100644
--- a/base/system_monitor/system_monitor.h
+++ b/base/system_monitor/system_monitor.h
@@ -90,15 +90,26 @@ class BASE_EXPORT SystemMonitor {
     virtual ~PowerObserver() {}
   };
 
+  class BASE_EXPORT DevicesChangedObserver {
+   public:
+    // Notification that the devices connected to the system have changed.
+    virtual void OnDevicesChanged() {}
+
+   protected:
+    virtual ~DevicesChangedObserver() {}
+  };
+
   // Add a new observer.
   // Can be called from any thread.
   // Must not be called from within a notification callback.
-  void AddObserver(PowerObserver* obs);
+  void AddPowerObserver(PowerObserver* obs);
+  void AddDevicesChangedObserver(DevicesChangedObserver* obs);
 
   // Remove an existing observer.
   // Can be called from any thread.
   // Must not be called from within a notification callback.
-  void RemoveObserver(PowerObserver* obs);
+  void RemovePowerObserver(PowerObserver* obs);
+  void RemoveDevicesChangedObserver(DevicesChangedObserver* obs);
 
 #if defined(OS_WIN)
   // Windows-specific handling of a WM_POWERBROADCAST message.
@@ -110,6 +121,9 @@ class BASE_EXPORT SystemMonitor {
   // Cross-platform handling of a power event.
   void ProcessPowerMessage(PowerEvent event_id);
 
+  // Cross-platform handling of a device change event.
+  void ProcessDevicesChanged();
+
  private:
 #if defined(OS_MACOSX)
   void PlatformInit();
@@ -126,11 +140,14 @@ class BASE_EXPORT SystemMonitor {
   void BatteryCheck();
 
   // Functions to trigger notifications.
+  void NotifyDevicesChanged();
   void NotifyPowerStateChange();
   void NotifySuspend();
   void NotifyResume();
 
-  scoped_refptr<ObserverListThreadSafe<PowerObserver> > observer_list_;
+  scoped_refptr<ObserverListThreadSafe<PowerObserver> > power_observer_list_;
+  scoped_refptr<ObserverListThreadSafe<DevicesChangedObserver> >
+      devices_changed_observer_list_;
   bool battery_in_use_;
   bool suspended_;
 
diff --git a/base/system_monitor/system_monitor_unittest.cc b/base/system_monitor/system_monitor_unittest.cc
index f4a4e73..1d5d6af 100644
--- a/base/system_monitor/system_monitor_unittest.cc
+++ b/base/system_monitor/system_monitor_unittest.cc
@@ -55,7 +55,7 @@ TEST(SystemMonitor, PowerNotifications) {
   SystemMonitor system_monitor;
   PowerTest test[kObservers];
   for (int index = 0; index < kObservers; ++index)
-    system_monitor.AddObserver(&test[index]);
+    system_monitor.AddPowerObserver(&test[index]);
 
   // Send a bunch of power changes.  Since the battery power hasn't
   // actually changed, we shouldn't get notifications.
@@ -90,4 +90,49 @@ TEST(SystemMonitor, PowerNotifications) {
   EXPECT_EQ(test[0].resumes(), 1);
 }
 
+class DevicesChangedTest : public SystemMonitor::DevicesChangedObserver {
+ public:
+  DevicesChangedTest()
+      : changes_(0) {
+  }
+
+  // DevicesChangedObserver callbacks.
+  virtual void OnDevicesChanged() OVERRIDE {
+    changes_++;
+  }
+
+  // Test status counts.
+  int changes() const { return changes_; }
+
+ private:
+  int changes_;  // Count of OnDevicesChanged notifications.
+
+  DISALLOW_COPY_AND_ASSIGN(DevicesChangedTest);
+};
+
+TEST(SystemMonitor, DeviceChangeNotifications) {
+  const int kObservers = 5;
+
+  // Initialize a message loop for this to run on.
+  MessageLoop loop;
+
+#if defined(OS_MACOSX)
+  SystemMonitor::AllocateSystemIOPorts();
+#endif
+
+  SystemMonitor system_monitor;
+  DevicesChangedTest test[kObservers];
+  for (int index = 0; index < kObservers; ++index)
+    system_monitor.AddDevicesChangedObserver(&test[index]);
+
+  system_monitor.ProcessDevicesChanged();
+  loop.RunAllPending();
+  EXPECT_EQ(1, test[0].changes());
+
+  system_monitor.ProcessDevicesChanged();
+  system_monitor.ProcessDevicesChanged();
+  loop.RunAllPending();
+  EXPECT_EQ(3, test[0].changes());
+}
+
 }  // namespace base