Do not use virtual function to request shutdown

Would make it easier to port to other platforms.

atom/browser/api/atom_api_power_monitor.cc

@@ -16,6 +16,11 @@ namespace atom {
 namespace api {
 
 PowerMonitor::PowerMonitor(v8::Isolate* isolate) {
+#if defined(OS_LINUX)
+  SetShutdownHandler(base::Bind(&PowerMonitor::ShouldShutdown,
+                                // Passed to base class, no need for weak ptr.
+                                base::Unretained(this)));
+#endif
   base::PowerMonitor::Get()->AddObserver(this);
   Init(isolate);
 }
@@ -24,6 +29,20 @@ PowerMonitor::~PowerMonitor() {
   base::PowerMonitor::Get()->RemoveObserver(this);
 }
 
+bool PowerMonitor::ShouldShutdown() {
+  return Emit("shutdown");
+}
+
+#if defined(OS_LINUX)
+void PowerMonitor::BlockShutdown() {
+  PowerObserverLinux::BlockShutdown();
+}
+
+void PowerMonitor::UnblockShutdown() {
+  PowerObserverLinux::UnblockShutdown();
+}
+#endif
+
 void PowerMonitor::OnPowerStateChange(bool on_battery_power) {
   if (on_battery_power)
     Emit("on-battery");
@@ -39,12 +58,6 @@ void PowerMonitor::OnResume() {
   Emit("resume");
 }
 
-#if defined(OS_LINUX)
-bool PowerMonitor::OnShutdown() {
-  return Emit("shutdown");
-}
-#endif
-
 // static
 v8::Local<v8::Value> PowerMonitor::Create(v8::Isolate* isolate) {
   if (!Browser::Get()->is_ready()) {

atom/browser/api/atom_api_power_monitor.h

@@ -26,16 +26,20 @@ class PowerMonitor : public mate::TrackableObject<PowerMonitor>,
   explicit PowerMonitor(v8::Isolate* isolate);
   ~PowerMonitor() override;
 
+  // Called by native calles.
+  bool ShouldShutdown();
+
+#if defined(OS_LINUX)
+  // Private JS APIs.
+  void BlockShutdown();
+  void UnblockShutdown();
+#endif
+
   // base::PowerObserver implementations:
   void OnPowerStateChange(bool on_battery_power) override;
   void OnSuspend() override;
   void OnResume() override;
 
-#if defined(OS_LINUX)
-  // atom::PowerObserver
-  bool OnShutdown() override;
-#endif
-
  private:
   DISALLOW_COPY_AND_ASSIGN(PowerMonitor);
 };

atom/browser/lib/power_observer_linux.cc

@@ -114,6 +114,10 @@ void PowerObserverLinux::UnblockShutdown() {
   shutdown_lock_.reset();
 }
 
+void PowerObserverLinux::SetShutdownHandler(base::Callback<bool()> handler) {
+  should_shutdown_ = std::move(handler);
+}
+
 void PowerObserverLinux::OnInhibitResponse(base::ScopedFD* scoped_fd,
                                            dbus::Response* response) {
   dbus::MessageReader reader(response);
@@ -144,7 +148,7 @@ void PowerObserverLinux::OnPrepareForShutdown(dbus::Signal* signal) {
     return;
   }
   if (shutting_down) {
-    if (!OnShutdown()) {
+    if (!should_shutdown_ || !should_shutdown_.Run()) {
       // The user didn't try to prevent shutdown. Release the lock and allow the
       // shutdown to continue normally.
       shutdown_lock_.reset();

atom/browser/lib/power_observer_linux.h

@@ -26,7 +26,7 @@ class PowerObserverLinux : public base::PowerObserver {
   void BlockShutdown();
   void UnblockShutdown();
 
-  virtual bool OnShutdown() { return false; }
+  void SetShutdownHandler(base::Callback<bool()> should_shutdown);
 
  private:
   void OnLoginServiceAvailable(bool available);
@@ -37,6 +37,8 @@ class PowerObserverLinux : public base::PowerObserver {
                          const std::string& signal,
                          bool success);
 
+  base::Callback<bool()> should_shutdown_;
+
   scoped_refptr<dbus::Bus> bus_;
   scoped_refptr<dbus::ObjectProxy> logind_;
   std::string lock_owner_name_;