sessionMode: Remove lock-screen mode

Now that the screen shield is gone (at least, as it used to
be), the corresponding session mode is not necessary anymore
as well.

Remove the 'lock-screen' session mode, and the corresponding
CSS.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/872

data/theme/gnome-shell-sass/widgets/_panel.scss

@@ -15,8 +15,7 @@ $panel_height: 1.86em;
 
   // transparent panel on lock & login screens
   &.unlock-screen,
-  &.login-screen,
-  &.lock-screen {
+  &.login-screen {
     background-color: transparent;
 
     .panel-corner {
@@ -77,8 +76,7 @@ $panel_height: 1.86em;
 
     // lock & login screen styles
     .unlock-screen &,
-    .login-screen &,
-    .lock-screen & {
+    .login-screen & {
       color: lighten($fg_color, 10%);
       &:focus, &:hover, &:active { color: lighten($fg_color, 10%); }
     }

data/theme/gnome-shell-sass/widgets/_screen-shield.scss

@@ -50,8 +50,6 @@ $_unlockdialog_shadow: 0px 0px 6px rgba(0, 0, 0, 0.726);
 
 .unlock-dialog-notification-count-text { padding: 0px 0px 0px 12px; }
 
-#panel.lock-screen { background-color: transparentize($osd_bg_color, 0.5); }
-
 .screen-shield-background { //just the shadow, really
   background: black;
   box-shadow: 0px 2px 4px rgba(0,0,0,0.6);

js/ui/screenShield.js

@@ -362,9 +362,6 @@ var ScreenShield = class {
     }
 
     _hideLockScreenComplete() {
-        if (Main.sessionMode.currentMode == 'lock-screen')
-            Main.sessionMode.popMode('lock-screen');
-
         this._lockScreenState = MessageTray.State.HIDDEN;
         this._lockScreenGroup.hide();
 
@@ -470,9 +467,6 @@ var ScreenShield = class {
         }
 
         this._lockScreenGroup.grab_key_focus();
-
-        if (Main.sessionMode.currentMode != 'lock-screen')
-            Main.sessionMode.pushMode('lock-screen');
     }
 
     _lockScreenShown(params) {
@@ -536,8 +530,6 @@ var ScreenShield = class {
     _continueDeactivate(animate) {
         this._hideLockScreen(animate);
 
-        if (Main.sessionMode.currentMode == 'lock-screen')
-            Main.sessionMode.popMode('lock-screen');
         if (Main.sessionMode.currentMode == 'unlock-dialog')
             Main.sessionMode.popMode('unlock-dialog');
 
@@ -605,8 +597,7 @@ var ScreenShield = class {
 
         this.actor.show();
 
-        if (Main.sessionMode.currentMode != 'unlock-dialog' &&
-            Main.sessionMode.currentMode != 'lock-screen') {
+        if (Main.sessionMode.currentMode !== 'unlock-dialog') {
             this._isGreeter = Main.sessionMode.isGreeter;
             if (!this._isGreeter)
                 Main.sessionMode.pushMode('unlock-dialog');

js/ui/sessionMode.js

@@ -53,19 +53,6 @@ const _modes = {
         panelStyle: 'login-screen',
     },
 
-    'lock-screen': {
-        isLocked: true,
-        isGreeter: undefined,
-        unlockDialog: undefined,
-        components: ['polkitAgent', 'telepathyClient'],
-        panel: {
-            left: [],
-            center: [],
-            right: ['aggregateMenu'],
-        },
-        panelStyle: 'lock-screen',
-    },
-
     'unlock-dialog': {
         isLocked: true,
         unlockDialog: undefined,