Backed out changeset 2d2ee0638f59 (bug 1373492) for failing browser_inspector_highlighter-eyedropper-xul.js. r=backout

devtools/client/framework/toolbox-options.js

@@ -322,6 +322,11 @@ OptionsPanel.prototype = {
       label: "Enable new debugger frontend",
       id: "devtools-new-debugger",
       parentId: "debugger-options"
+    }, {
+      pref: "devtools.layoutview.enabled",
+      label: "Enable layout panel",
+      id: "devtools-layout-panel",
+      parentId: "inspector-options"
     }];
 
     let createPreferenceOption = ({pref, label, id}) => {

devtools/client/inspector/boxmodel/test/head.js

@@ -11,8 +11,10 @@ Services.scriptloader.loadSubScript(
   "chrome://mochitests/content/browser/devtools/client/inspector/test/head.js",
   this);
 
+Services.prefs.setBoolPref("devtools.layoutview.enabled", true);
 Services.prefs.setIntPref("devtools.toolbox.footer.height", 350);
 registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("devtools.layoutview.enabled");
   Services.prefs.clearUserPref("devtools.toolbox.footer.height");
 });
 

devtools/client/inspector/grids/test/head.js

@@ -16,9 +16,11 @@ Services.scriptloader.loadSubScript(
   "chrome://mochitests/content/browser/devtools/client/framework/test/shared-redux-head.js",
   this);
 
+Services.prefs.setBoolPref("devtools.layoutview.enabled", true);
 Services.prefs.setBoolPref("devtools.promote.layoutview.showPromoteBar", false);
 Services.prefs.setIntPref("devtools.toolbox.footer.height", 350);
 registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("devtools.layoutview.enabled");
   Services.prefs.clearUserPref("devtools.promote.layoutview.showPromoteBar");
   Services.prefs.clearUserPref("devtools.toolbox.footer.height");
 });

devtools/client/inspector/inspector.js

@@ -620,12 +620,14 @@ Inspector.prototype = {
       INSPECTOR_L10N.getStr("inspector.sidebar.computedViewTitle"),
       defaultTab == "computedview");
 
+    if (Services.prefs.getBoolPref("devtools.layoutview.enabled")) {
       // Grid and layout panels aren't lazy-loaded as their module end up
       // calling inspector.addSidebarTab
       this.gridInspector = new GridInspector(this, this.panelWin);
 
       const LayoutView = this.browserRequire("devtools/client/inspector/layout/layout");
       this.layoutview = new LayoutView(this, this.panelWin);
+    }
 
     if (this.target.form.animationsActor) {
       this.sidebar.addFrameTab(

devtools/client/locales/en-US/layout.properties

@@ -4,6 +4,8 @@
 
 # LOCALIZATION NOTE This file contains the Layout Inspector strings.
 # The Layout Inspector is a panel accessible in the Inspector sidebar.
+# The Layout Inspector may need to be enabled in about:config by setting
+# devtools.layoutview.enabled to true.
 
 # LOCALIZATION NOTE (layout.cannotShowGridOutline, layout.cannotSHowGridOutline.title):
 # In the case where the grid outline cannot be effectively displayed.

devtools/client/preferences/devtools.js

@@ -68,6 +68,9 @@ pref("devtools.inspector.colorWidget.enabled", false);
 // Enable the Font Inspector
 pref("devtools.fontinspector.enabled", true);
 
+// Enable the Layout View
+pref("devtools.layoutview.enabled", false);
+
 // Counter to promote the inspector layout view.
 // @remove after release 56 (See Bug 1355747)
 pref("devtools.promote.layoutview", 1);