ScreenShield: tie the suspend inhibitor to our isActive property

The whole point of holding a suspend inhibitor is to be able to lock
before suspending.

Currently, when resuming we immediately take the inhibitor without
checking that we're locked which means that we won't be able to
release this inhibitor if we don't unlock at least once.

To prevent that and to better match the inhibitor's intention in the
first place, we can tie the inhibitor with not being locked. In
practice, we also want to let the locking animation finish before
suspending, so we'll tie the inhibitor with not being active
instead.

https://bugzilla.gnome.org/show_bug.cgi?id=749228

js/ui/screenShield.js

@@ -507,12 +507,9 @@ const ScreenShield = new Lang.Class({
                                                       this._liftShield(true, 0);
                                               }));
 
-        this._inhibitor = null;
-        this._aboutToSuspend = false;
         this._loginManager = LoginManager.getLoginManager();
         this._loginManager.connect('prepare-for-sleep',
                                    Lang.bind(this, this._prepareForSleep));
-        this._inhibitSuspend();
 
         this._loginManager.getCurrentSessionProxy(Lang.bind(this,
             function(sessionProxy) {
@@ -522,6 +519,7 @@ const ScreenShield = new Lang.Class({
             }));
 
         this._settings = new Gio.Settings({ schema_id: SCREENSAVER_SCHEMA });
+        this._settings.connect('changed::' + LOCK_ENABLED_KEY, Lang.bind(this, this._syncInhibitor));
 
         this._isModal = false;
         this._hasLockScreen = false;
@@ -547,6 +545,18 @@ const ScreenShield = new Lang.Class({
 
         this.idleMonitor = Meta.IdleMonitor.get_core();
         this._cursorTracker = Meta.CursorTracker.get_for_screen(global.screen);
+
+        this._syncInhibitor();
+    },
+
+    _setActive: function(active) {
+        let prevIsActive = this._isActive;
+        this._isActive = active;
+
+        if (prevIsActive != this._isActive)
+            this.emit('active-changed');
+
+        this._syncInhibitor();
     },
 
     _createBackground: function(monitorIndex) {
@@ -664,33 +674,27 @@ const ScreenShield = new Lang.Class({
         return Clutter.EVENT_STOP;
     },
 
-    _inhibitSuspend: function() {
+    _syncInhibitor: function() {
+        let inhibit = (!this._isActive && this._settings.get_boolean(LOCK_ENABLED_KEY));
+        if (inhibit) {
             this._loginManager.inhibit(_("GNOME needs to lock the screen"),
                                        Lang.bind(this, function(inhibitor) {
                                            if (this._inhibitor)
                                                this._inhibitor.close(null);
                                            this._inhibitor = inhibitor;
                                        }));
-    },
+        } else {
-
-    _uninhibitSuspend: function() {
             if (this._inhibitor)
                 this._inhibitor.close(null);
             this._inhibitor = null;
+        }
     },
 
     _prepareForSleep: function(loginManager, aboutToSuspend) {
-        this._aboutToSuspend = aboutToSuspend;
-
         if (aboutToSuspend) {
-            if (!this._settings.get_boolean(LOCK_ENABLED_KEY)) {
+            if (this._settings.get_boolean(LOCK_ENABLED_KEY))
-                this._uninhibitSuspend();
-                return;
-            }
                 this.lock(true);
         } else {
-            this._inhibitSuspend();
-
             this._wakeUpScreen();
         }
     },
@@ -1085,15 +1089,7 @@ const ScreenShield = new Lang.Class({
     },
 
     _completeLockScreenShown: function() {
-        let prevIsActive = this._isActive;
+        this._setActive(true);
-        this._isActive = true;
-
-        if (prevIsActive != this._isActive)
-            this.emit('active-changed');
-
-        if (this._aboutToSuspend)
-            this._uninhibitSuspend();
-
         this.emit('lock-screen-shown');
     },
 
@@ -1187,8 +1183,7 @@ const ScreenShield = new Lang.Class({
             // gnome-settings-daemon will stop blanking the screen
 
             this._activationTime = 0;
-            this._isActive = false;
+            this._setActive(false);
-            this.emit('active-changed');
             return;
         }
 
@@ -1231,9 +1226,8 @@ const ScreenShield = new Lang.Class({
         }
 
         this._activationTime = 0;
-        this._isActive = false;
+        this._setActive(false);
         this._isLocked = false;
-        this.emit('active-changed');
         this.emit('locked-changed');
         global.set_runtime_state(LOCKED_STATE_STR, null);
     },