--- a/devtools/client/debugger/new/test/mochitest/browser.ini
+++ b/devtools/client/debugger/new/test/mochitest/browser.ini
@@ -62,16 +62,18 @@ support-files =
 [browser_dbg-async-stepping.js]
 [browser_dbg-breaking.js]
 [browser_dbg-breaking-from-console.js]
 [browser_dbg-breakpoints.js]
 [browser_dbg-breakpoints-toggle.js]
 [browser_dbg-breakpoints-reloading.js]
 skip-if = true # Bug 1383576
 [browser_dbg-breakpoints-cond.js]
+[browser_dbg-browser-content-toolbox.js]
+skip-if = !e10s # This test is only valid in e10s
 [browser_dbg-call-stack.js]
 [browser_dbg-scopes.js]
 [browser_dbg-chrome-create.js]
 [browser_dbg-chrome-debugging.js]
 skip-if = debug # bug 1374187
 [browser_dbg-console.js]
 [browser_dbg-debugger-buttons.js]
 [browser_dbg-editor-gutter.js]
@@ -102,10 +104,10 @@ skip-if = true # Bug 1393121, 1393299
 [browser_dbg-sourcemaps.js]
 [browser_dbg-sourcemaps-reloading.js]
 [browser_dbg-sourcemaps2.js]
 [browser_dbg-sourcemaps-bogus.js]
 [browser_dbg-sources.js]
 [browser_dbg-tabs.js]
 [browser_dbg-toggling-tools.js]
 [browser_dbg-wasm-sourcemaps.js]
-skip-if = true 
+skip-if = true
 [browser_dbg-reload.js]

new file mode 100644
--- /dev/null
+++ b/devtools/client/debugger/new/test/mochitest/browser_dbg-browser-content-toolbox.js
@@ -0,0 +1,73 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the debugger is succesfully loaded in the Browser Content Toolbox.
+ */
+
+const {gDevToolsBrowser} = require("devtools/client/framework/devtools-browser");
+
+function toggleBreakpoint(dbg, index) {
+  const bp = findElement(dbg, "breakpointItem", index);
+  const input = bp.querySelector("input");
+  input.click();
+}
+
+async function disableBreakpoint(dbg, index) {
+  const disabled = waitForDispatch(dbg, "DISABLE_BREAKPOINT");
+  toggleBreakpoint(dbg, index);
+  await disabled;
+}
+
+async function enableBreakpoint(dbg, index) {
+  const enabled = waitForDispatch(dbg, "ENABLE_BREAKPOINT");
+  toggleBreakpoint(dbg, index);
+  await enabled;
+}
+
+function findBreakpoint(dbg, url, line) {
+  const { selectors: { getBreakpoint }, getState } = dbg;
+  const source = findSource(dbg, url);
+  return getBreakpoint(getState(), { sourceId: source.id, line });
+}
+
+add_task(async function() {
+  clearDebuggerPreferences();
+
+  info("Open a tab pointing to doc-scripts.html");
+  await addTab(EXAMPLE_URL + "doc-scripts.html");
+
+  info("Open the Browser Content Toolbox");
+  let toolbox = await gDevToolsBrowser.openContentProcessToolbox(gBrowser);
+
+  info("Wait for the debugger to be ready");
+  await toolbox.getPanelWhenReady("jsdebugger");
+
+  let dbg = createDebuggerContext(toolbox);
+  ok(dbg, "Debugger context is available");
+
+  info("Create a breakpoint");
+  await selectSource(dbg, "simple2");
+  await addBreakpoint(dbg, "simple2", 3);
+
+  info("Disable the breakpoint");
+  await disableBreakpoint(dbg, 1);
+  let bp = findBreakpoint(dbg, "simple2", 3);
+  is(bp.disabled, true, "breakpoint is disabled");
+
+  info("Enable the breakpoint");
+  await enableBreakpoint(dbg, 1);
+  bp = findBreakpoint(dbg, "simple2", 3);
+  is(bp.disabled, false, "breakpoint is enabled");
+
+  info("Close the browser toolbox window");
+  let onToolboxDestroyed = toolbox.once("destroyed");
+  toolbox.win.top.close();
+  await onToolboxDestroyed;
+
+  info("Toolbox is destroyed");
+});

--- a/devtools/client/debugger/new/test/mochitest/head.js
+++ b/devtools/client/debugger/new/test/mochitest/head.js
@@ -361,33 +361,40 @@ function createDebuggerContext(toolbox) 
     getState: store.getState,
     store: store,
     client: client,
     toolbox: toolbox,
     win: win
   };
 }
 
+
+/**
+ * Clear all the debugger related preferences.
+ */
+function clearDebuggerPreferences() {
+  Services.prefs.clearUserPref("devtools.debugger.pause-on-exceptions");
+  Services.prefs.clearUserPref("devtools.debugger.ignore-caught-exceptions");
+  Services.prefs.clearUserPref("devtools.debugger.tabs");
+  Services.prefs.clearUserPref("devtools.debugger.pending-selected-location");
+  Services.prefs.clearUserPref("devtools.debugger.pending-breakpoints");
+  Services.prefs.clearUserPref("devtools.debugger.expressions");
+}
+
 /**
  * Intilializes the debugger.
  *
  * @memberof mochitest
  * @param {String} url
- * @param {Array} sources
  * @return {Promise} dbg
  * @static
  */
-function initDebugger(url, ...sources) {
+function initDebugger(url) {
   return Task.spawn(function*() {
-    Services.prefs.clearUserPref("devtools.debugger.pause-on-exceptions");
-    Services.prefs.clearUserPref("devtools.debugger.ignore-caught-exceptions");
-    Services.prefs.clearUserPref("devtools.debugger.tabs");
-    Services.prefs.clearUserPref("devtools.debugger.pending-selected-location");
-    Services.prefs.clearUserPref("devtools.debugger.pending-breakpoints");
-    Services.prefs.clearUserPref("devtools.debugger.expressions");
+    clearDebuggerPreferences();
     const toolbox = yield openNewTabAndToolbox(EXAMPLE_URL + url, "jsdebugger");
     return createDebuggerContext(toolbox);
   });
 }
 
 window.resumeTest = undefined;
 /**
  * Pause the test and let you interact with the debugger.