diff --git a/dom/serviceworkers/ServiceWorkerPrivate.cpp b/dom/serviceworkers/ServiceWorkerPrivate.cpp
index 542a67a18780..05b3df95c6eb 100644
--- a/dom/serviceworkers/ServiceWorkerPrivate.cpp
+++ b/dom/serviceworkers/ServiceWorkerPrivate.cpp
@@ -22,6 +22,7 @@
 #include "nsQueryObject.h"
 #include "nsStreamUtils.h"
 #include "nsStringStream.h"
+#include "WorkerDebugger.h"
 #include "WorkerRunnable.h"
 #include "WorkerScope.h"
 #include "mozilla/Assertions.h"
diff --git a/dom/workers/ScriptLoader.h b/dom/workers/ScriptLoader.h
index 46a9da30295e..c5bf3fda02bb 100644
--- a/dom/workers/ScriptLoader.h
+++ b/dom/workers/ScriptLoader.h
@@ -25,6 +25,8 @@ class ErrorResult;
 
 BEGIN_WORKERS_NAMESPACE
 
+struct WorkerLoadInfo;
+
 enum WorkerScriptType {
   WorkerScript,
   DebuggerScript
diff --git a/dom/workers/WorkerDebugger.cpp b/dom/workers/WorkerDebugger.cpp
new file mode 100644
index 000000000000..9a36883a559d
--- /dev/null
+++ b/dom/workers/WorkerDebugger.cpp
@@ -0,0 +1,477 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WorkerDebugger.h"
+
+#include "mozilla/dom/MessageEvent.h"
+#include "mozilla/dom/MessageEventBinding.h"
+#include "nsProxyRelease.h"
+#include "nsQueryObject.h"
+#include "nsThreadUtils.h"
+#include "ScriptLoader.h"
+#include "WorkerCommon.h"
+#include "WorkerPrivate.h"
+#include "WorkerRunnable.h"
+#include "WorkerScope.h"
+
+namespace mozilla {
+namespace dom {
+namespace workers {
+
+namespace {
+
+class DebuggerMessageEventRunnable : public WorkerDebuggerRunnable
+{
+  nsString mMessage;
+
+public:
+  DebuggerMessageEventRunnable(WorkerPrivate* aWorkerPrivate,
+                               const nsAString& aMessage)
+  : WorkerDebuggerRunnable(aWorkerPrivate),
+    mMessage(aMessage)
+  {
+  }
+
+private:
+  virtual bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    WorkerDebuggerGlobalScope* globalScope = aWorkerPrivate->DebuggerGlobalScope();
+    MOZ_ASSERT(globalScope);
+
+    JS::Rooted<JSString*> message(aCx, JS_NewUCStringCopyN(aCx, mMessage.get(),
+                                                           mMessage.Length()));
+    if (!message) {
+      return false;
+    }
+    JS::Rooted<JS::Value> data(aCx, JS::StringValue(message));
+
+    RefPtr<MessageEvent> event = new MessageEvent(globalScope, nullptr,
+                                                  nullptr);
+    event->InitMessageEvent(nullptr,
+                            NS_LITERAL_STRING("message"),
+                            false, // canBubble
+                            true, // cancelable
+                            data,
+                            EmptyString(),
+                            EmptyString(),
+                            nullptr,
+                            Sequence<OwningNonNull<MessagePort>>());
+    event->SetTrusted(true);
+
+    nsCOMPtr<nsIDOMEvent> domEvent = do_QueryObject(event);
+    bool dummy;
+    globalScope->DispatchEvent(domEvent, &dummy);
+    return true;
+  }
+};
+
+class CompileDebuggerScriptRunnable final : public WorkerDebuggerRunnable
+{
+  nsString mScriptURL;
+
+public:
+  CompileDebuggerScriptRunnable(WorkerPrivate* aWorkerPrivate,
+                                const nsAString& aScriptURL)
+  : WorkerDebuggerRunnable(aWorkerPrivate),
+    mScriptURL(aScriptURL)
+  { }
+
+private:
+  virtual bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    aWorkerPrivate->AssertIsOnWorkerThread();
+
+    WorkerDebuggerGlobalScope* globalScope =
+      aWorkerPrivate->CreateDebuggerGlobalScope(aCx);
+    if (!globalScope) {
+      NS_WARNING("Failed to make global!");
+      return false;
+    }
+
+    if (NS_WARN_IF(!aWorkerPrivate->EnsureClientSource())) {
+      return false;
+    }
+
+    JS::Rooted<JSObject*> global(aCx, globalScope->GetWrapper());
+
+    ErrorResult rv;
+    JSAutoCompartment ac(aCx, global);
+    scriptloader::LoadMainScript(aWorkerPrivate, mScriptURL,
+                                 DebuggerScript, rv);
+    rv.WouldReportJSException();
+    // Explicitly ignore NS_BINDING_ABORTED on rv.  Or more precisely, still
+    // return false and don't SetWorkerScriptExecutedSuccessfully() in that
+    // case, but don't throw anything on aCx.  The idea is to not dispatch error
+    // events if our load is canceled with that error code.
+    if (rv.ErrorCodeIs(NS_BINDING_ABORTED)) {
+      rv.SuppressException();
+      return false;
+    }
+    // Make sure to propagate exceptions from rv onto aCx, so that they will get
+    // reported after we return.  We do this for all failures on rv, because now
+    // we're using rv to track all the state we care about.
+    if (rv.MaybeSetPendingException(aCx)) {
+      return false;
+    }
+
+    return true;
+  }
+};
+
+} // anonymous
+
+class WorkerDebugger::PostDebuggerMessageRunnable final : public Runnable
+{
+  WorkerDebugger *mDebugger;
+  nsString mMessage;
+
+public:
+  PostDebuggerMessageRunnable(WorkerDebugger* aDebugger,
+                              const nsAString& aMessage)
+    : mozilla::Runnable("PostDebuggerMessageRunnable")
+    , mDebugger(aDebugger)
+    , mMessage(aMessage)
+  {
+  }
+
+private:
+  ~PostDebuggerMessageRunnable()
+  { }
+
+  NS_IMETHOD
+  Run() override
+  {
+    mDebugger->PostMessageToDebuggerOnMainThread(mMessage);
+
+    return NS_OK;
+  }
+};
+
+class WorkerDebugger::ReportDebuggerErrorRunnable final : public Runnable
+{
+  WorkerDebugger *mDebugger;
+  nsString mFilename;
+  uint32_t mLineno;
+  nsString mMessage;
+
+public:
+  ReportDebuggerErrorRunnable(WorkerDebugger* aDebugger,
+                              const nsAString& aFilename,
+                              uint32_t aLineno,
+                              const nsAString& aMessage)
+    : Runnable("ReportDebuggerErrorRunnable")
+    , mDebugger(aDebugger)
+    , mFilename(aFilename)
+    , mLineno(aLineno)
+    , mMessage(aMessage)
+  {
+  }
+
+private:
+  ~ReportDebuggerErrorRunnable()
+  { }
+
+  NS_IMETHOD
+  Run() override
+  {
+    mDebugger->ReportErrorToDebuggerOnMainThread(mFilename, mLineno, mMessage);
+
+    return NS_OK;
+  }
+};
+
+WorkerDebugger::WorkerDebugger(WorkerPrivate* aWorkerPrivate)
+: mWorkerPrivate(aWorkerPrivate),
+  mIsInitialized(false)
+{
+  AssertIsOnMainThread();
+}
+
+WorkerDebugger::~WorkerDebugger()
+{
+  MOZ_ASSERT(!mWorkerPrivate);
+
+  if (!NS_IsMainThread()) {
+    for (size_t index = 0; index < mListeners.Length(); ++index) {
+      NS_ReleaseOnMainThreadSystemGroup(
+        "WorkerDebugger::mListeners", mListeners[index].forget());
+    }
+  }
+}
+
+NS_IMPL_ISUPPORTS(WorkerDebugger, nsIWorkerDebugger)
+
+NS_IMETHODIMP
+WorkerDebugger::GetIsClosed(bool* aResult)
+{
+  AssertIsOnMainThread();
+
+  *aResult = !mWorkerPrivate;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetIsChrome(bool* aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  *aResult = mWorkerPrivate->IsChromeWorker();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetIsInitialized(bool* aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  *aResult = mIsInitialized;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetParent(nsIWorkerDebugger** aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  WorkerPrivate* parent = mWorkerPrivate->GetParent();
+  if (!parent) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(mWorkerPrivate->IsDedicatedWorker());
+
+  nsCOMPtr<nsIWorkerDebugger> debugger = parent->Debugger();
+  debugger.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetType(uint32_t* aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  *aResult = mWorkerPrivate->Type();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetUrl(nsAString& aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  aResult = mWorkerPrivate->ScriptURL();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetWindow(mozIDOMWindow** aResult)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mWorkerPrivate->GetParent() || !mWorkerPrivate->IsDedicatedWorker()) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsPIDOMWindowInner> window = mWorkerPrivate->GetWindow();
+  window.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetPrincipal(nsIPrincipal** aResult)
+{
+  AssertIsOnMainThread();
+  MOZ_ASSERT(aResult);
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsCOMPtr<nsIPrincipal> prin = mWorkerPrivate->GetPrincipal();
+  prin.forget(aResult);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::GetServiceWorkerID(uint32_t* aResult)
+{
+  AssertIsOnMainThread();
+  MOZ_ASSERT(aResult);
+
+  if (!mWorkerPrivate || !mWorkerPrivate->IsServiceWorker()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  *aResult = mWorkerPrivate->ServiceWorkerID();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::Initialize(const nsAString& aURL)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!mIsInitialized) {
+    RefPtr<CompileDebuggerScriptRunnable> runnable =
+      new CompileDebuggerScriptRunnable(mWorkerPrivate, aURL);
+    if (!runnable->Dispatch()) {
+      return NS_ERROR_FAILURE;
+    }
+
+    mIsInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::PostMessageMoz(const nsAString& aMessage)
+{
+  AssertIsOnMainThread();
+
+  if (!mWorkerPrivate || !mIsInitialized) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  RefPtr<DebuggerMessageEventRunnable> runnable =
+    new DebuggerMessageEventRunnable(mWorkerPrivate, aMessage);
+  if (!runnable->Dispatch()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::AddListener(nsIWorkerDebuggerListener* aListener)
+{
+  AssertIsOnMainThread();
+
+  if (mListeners.Contains(aListener)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mListeners.AppendElement(aListener);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WorkerDebugger::RemoveListener(nsIWorkerDebuggerListener* aListener)
+{
+  AssertIsOnMainThread();
+
+  if (!mListeners.Contains(aListener)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mListeners.RemoveElement(aListener);
+  return NS_OK;
+}
+
+void
+WorkerDebugger::Close()
+{
+  MOZ_ASSERT(mWorkerPrivate);
+  mWorkerPrivate = nullptr;
+
+  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
+  for (size_t index = 0; index < listeners.Length(); ++index) {
+      listeners[index]->OnClose();
+  }
+}
+
+void
+WorkerDebugger::PostMessageToDebugger(const nsAString& aMessage)
+{
+  mWorkerPrivate->AssertIsOnWorkerThread();
+
+  RefPtr<PostDebuggerMessageRunnable> runnable =
+    new PostDebuggerMessageRunnable(this, aMessage);
+  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
+    NS_WARNING("Failed to post message to debugger on main thread!");
+  }
+}
+
+void
+WorkerDebugger::PostMessageToDebuggerOnMainThread(const nsAString& aMessage)
+{
+  AssertIsOnMainThread();
+
+  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
+  for (size_t index = 0; index < listeners.Length(); ++index) {
+    listeners[index]->OnMessage(aMessage);
+  }
+}
+
+void
+WorkerDebugger::ReportErrorToDebugger(const nsAString& aFilename,
+                                      uint32_t aLineno,
+                                      const nsAString& aMessage)
+{
+  mWorkerPrivate->AssertIsOnWorkerThread();
+
+  RefPtr<ReportDebuggerErrorRunnable> runnable =
+    new ReportDebuggerErrorRunnable(this, aFilename, aLineno, aMessage);
+  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
+    NS_WARNING("Failed to report error to debugger on main thread!");
+  }
+}
+
+void
+WorkerDebugger::ReportErrorToDebuggerOnMainThread(const nsAString& aFilename,
+                                                  uint32_t aLineno,
+                                                  const nsAString& aMessage)
+{
+  AssertIsOnMainThread();
+
+  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
+  for (size_t index = 0; index < listeners.Length(); ++index) {
+    listeners[index]->OnError(aFilename, aLineno, aMessage);
+  }
+
+  WorkerErrorReport report;
+  report.mMessage = aMessage;
+  report.mFilename = aFilename;
+  LogErrorToConsole(report, 0);
+}
+
+
+} // worker namespace
+} // dom namespace
+} // mozilla namespace
diff --git a/dom/workers/WorkerDebugger.h b/dom/workers/WorkerDebugger.h
new file mode 100644
index 000000000000..0fec61588aa2
--- /dev/null
+++ b/dom/workers/WorkerDebugger.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_workers_WorkerDebugger_h
+#define mozilla_dom_workers_WorkerDebugger_h
+
+#include "mozilla/dom/workers/WorkerCommon.h"
+#include "nsIWorkerDebugger.h"
+
+BEGIN_WORKERS_NAMESPACE
+
+class WorkerDebugger : public nsIWorkerDebugger
+{
+  class ReportDebuggerErrorRunnable;
+  class PostDebuggerMessageRunnable;
+
+  WorkerPrivate* mWorkerPrivate;
+  bool mIsInitialized;
+  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> mListeners;
+
+public:
+  explicit WorkerDebugger(WorkerPrivate* aWorkerPrivate);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIWORKERDEBUGGER
+
+  void
+  AssertIsOnParentThread();
+
+  void
+  Close();
+
+  void
+  PostMessageToDebugger(const nsAString& aMessage);
+
+  void
+  ReportErrorToDebugger(const nsAString& aFilename, uint32_t aLineno,
+                        const nsAString& aMessage);
+
+private:
+  virtual
+  ~WorkerDebugger();
+
+  void
+  PostMessageToDebuggerOnMainThread(const nsAString& aMessage);
+
+  void
+  ReportErrorToDebuggerOnMainThread(const nsAString& aFilename,
+                                    uint32_t aLineno,
+                                    const nsAString& aMessage);
+};
+
+END_WORKERS_NAMESPACE
+
+#endif // mozilla_dom_workers_WorkerDebugger_h
diff --git a/dom/workers/WorkerDebuggerManager.cpp b/dom/workers/WorkerDebuggerManager.cpp
index dfb907ac20c3..d6e9fc72cb7f 100644
--- a/dom/workers/WorkerDebuggerManager.cpp
+++ b/dom/workers/WorkerDebuggerManager.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/StaticPtr.h"
 
+#include "WorkerDebugger.h"
 #include "WorkerPrivate.h"
 
 USING_WORKERS_NAMESPACE
diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 4aa4471fe5b4..dd1c062979ce 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -28,7 +28,6 @@
 #include "nsIURI.h"
 #include "nsIURL.h"
 #include "nsIWeakReferenceUtils.h"
-#include "nsIWorkerDebugger.h"
 #include "nsIXPConnect.h"
 #include "nsPIDOMWindow.h"
 #include "nsGlobalWindow.h"
@@ -111,6 +110,7 @@
 #include "mozilla/dom/ServiceWorkerEvents.h"
 #include "mozilla/dom/ServiceWorkerManager.h"
 #include "SharedWorker.h"
+#include "WorkerDebugger.h"
 #include "WorkerDebuggerManager.h"
 #include "WorkerHolder.h"
 #include "WorkerNavigator.h"
@@ -275,69 +275,6 @@ struct WindowAction
   }
 };
 
-void
-LogErrorToConsole(const WorkerErrorReport& aReport, uint64_t aInnerWindowId)
-{
-  AssertIsOnMainThread();
-
-  RefPtr<nsScriptErrorBase> scriptError = new nsScriptError();
-  NS_WARNING_ASSERTION(scriptError, "Failed to create script error!");
-
-  if (scriptError) {
-    nsAutoCString category("Web Worker");
-    if (NS_FAILED(scriptError->InitWithWindowID(aReport.mMessage,
-                                                aReport.mFilename,
-                                                aReport.mLine,
-                                                aReport.mLineNumber,
-                                                aReport.mColumnNumber,
-                                                aReport.mFlags,
-                                                category,
-                                                aInnerWindowId))) {
-      NS_WARNING("Failed to init script error!");
-      scriptError = nullptr;
-    }
-
-    for (size_t i = 0, len = aReport.mNotes.Length(); i < len; i++) {
-      const WorkerErrorNote& note = aReport.mNotes.ElementAt(i);
-
-      nsScriptErrorNote* noteObject = new nsScriptErrorNote();
-      noteObject->Init(note.mMessage, note.mFilename,
-                       note.mLineNumber, note.mColumnNumber);
-      scriptError->AddNote(noteObject);
-    }
-  }
-
-  nsCOMPtr<nsIConsoleService> consoleService =
-    do_GetService(NS_CONSOLESERVICE_CONTRACTID);
-  NS_WARNING_ASSERTION(consoleService, "Failed to get console service!");
-
-  if (consoleService) {
-    if (scriptError) {
-      if (NS_SUCCEEDED(consoleService->LogMessage(scriptError))) {
-        return;
-      }
-      NS_WARNING("LogMessage failed!");
-    } else if (NS_SUCCEEDED(consoleService->LogStringMessage(
-                              aReport.mMessage.BeginReading()))) {
-      return;
-    }
-    NS_WARNING("LogStringMessage failed!");
-  }
-
-  NS_ConvertUTF16toUTF8 msg(aReport.mMessage);
-  NS_ConvertUTF16toUTF8 filename(aReport.mFilename);
-
-  static const char kErrorString[] = "JS error in Web Worker: %s [%s:%u]";
-
-#ifdef ANDROID
-  __android_log_print(ANDROID_LOG_INFO, "Gecko", kErrorString, msg.get(),
-                      filename.get(), aReport.mLineNumber);
-#endif
-
-  fprintf(stderr, kErrorString, msg.get(), filename.get(), aReport.mLineNumber);
-  fflush(stderr);
-}
-
 class WorkerFinishedRunnable final : public WorkerControlRunnable
 {
   WorkerPrivate* mFinishedWorker;
@@ -594,105 +531,6 @@ private:
   }
 };
 
-class CompileDebuggerScriptRunnable final : public WorkerDebuggerRunnable
-{
-  nsString mScriptURL;
-
-public:
-  CompileDebuggerScriptRunnable(WorkerPrivate* aWorkerPrivate,
-                                const nsAString& aScriptURL)
-  : WorkerDebuggerRunnable(aWorkerPrivate),
-    mScriptURL(aScriptURL)
-  { }
-
-private:
-  virtual bool
-  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
-  {
-    aWorkerPrivate->AssertIsOnWorkerThread();
-
-    WorkerDebuggerGlobalScope* globalScope =
-      aWorkerPrivate->CreateDebuggerGlobalScope(aCx);
-    if (!globalScope) {
-      NS_WARNING("Failed to make global!");
-      return false;
-    }
-
-    if (NS_WARN_IF(!aWorkerPrivate->EnsureClientSource())) {
-      return false;
-    }
-
-    JS::Rooted<JSObject*> global(aCx, globalScope->GetWrapper());
-
-    ErrorResult rv;
-    JSAutoCompartment ac(aCx, global);
-    scriptloader::LoadMainScript(aWorkerPrivate, mScriptURL,
-                                 DebuggerScript, rv);
-    rv.WouldReportJSException();
-    // Explicitly ignore NS_BINDING_ABORTED on rv.  Or more precisely, still
-    // return false and don't SetWorkerScriptExecutedSuccessfully() in that
-    // case, but don't throw anything on aCx.  The idea is to not dispatch error
-    // events if our load is canceled with that error code.
-    if (rv.ErrorCodeIs(NS_BINDING_ABORTED)) {
-      rv.SuppressException();
-      return false;
-    }
-    // Make sure to propagate exceptions from rv onto aCx, so that they will get
-    // reported after we return.  We do this for all failures on rv, because now
-    // we're using rv to track all the state we care about.
-    if (rv.MaybeSetPendingException(aCx)) {
-      return false;
-    }
-
-    return true;
-  }
-};
-
-class DebuggerMessageEventRunnable : public WorkerDebuggerRunnable {
-  nsString mMessage;
-
-public:
-  DebuggerMessageEventRunnable(WorkerPrivate* aWorkerPrivate,
-                               const nsAString& aMessage)
-  : WorkerDebuggerRunnable(aWorkerPrivate),
-    mMessage(aMessage)
-  {
-  }
-
-private:
-  virtual bool
-  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
-  {
-    WorkerDebuggerGlobalScope* globalScope = aWorkerPrivate->DebuggerGlobalScope();
-    MOZ_ASSERT(globalScope);
-
-    JS::Rooted<JSString*> message(aCx, JS_NewUCStringCopyN(aCx, mMessage.get(),
-                                                           mMessage.Length()));
-    if (!message) {
-      return false;
-    }
-    JS::Rooted<JS::Value> data(aCx, JS::StringValue(message));
-
-    RefPtr<MessageEvent> event = new MessageEvent(globalScope, nullptr,
-                                                    nullptr);
-    event->InitMessageEvent(nullptr,
-                            NS_LITERAL_STRING("message"),
-                            false, // canBubble
-                            true, // cancelable
-                            data,
-                            EmptyString(),
-                            EmptyString(),
-                            nullptr,
-                            Sequence<OwningNonNull<MessagePort>>());
-    event->SetTrusted(true);
-
-    nsCOMPtr<nsIDOMEvent> domEvent = do_QueryObject(event);
-    bool dummy;
-    globalScope->DispatchEvent(domEvent, &dummy);
-    return true;
-  }
-};
-
 class NotifyRunnable final : public WorkerControlRunnable
 {
   Status mStatus;
@@ -3484,352 +3322,6 @@ WorkerPrivateParent<Derived>::PrincipalIsValid() const
 }
 #endif
 
-class PostDebuggerMessageRunnable final : public Runnable
-{
-  WorkerDebugger *mDebugger;
-  nsString mMessage;
-
-public:
-  PostDebuggerMessageRunnable(WorkerDebugger* aDebugger,
-                              const nsAString& aMessage)
-    : mozilla::Runnable("PostDebuggerMessageRunnable")
-    , mDebugger(aDebugger)
-    , mMessage(aMessage)
-  {
-  }
-
-private:
-  ~PostDebuggerMessageRunnable()
-  { }
-
-  NS_IMETHOD
-  Run() override
-  {
-    mDebugger->PostMessageToDebuggerOnMainThread(mMessage);
-
-    return NS_OK;
-  }
-};
-
-class ReportDebuggerErrorRunnable final : public Runnable
-{
-  WorkerDebugger *mDebugger;
-  nsString mFilename;
-  uint32_t mLineno;
-  nsString mMessage;
-
-public:
-  ReportDebuggerErrorRunnable(WorkerDebugger* aDebugger,
-                              const nsAString& aFilename,
-                              uint32_t aLineno,
-                              const nsAString& aMessage)
-    : mozilla::Runnable("ReportDebuggerErrorRunnable")
-    , mDebugger(aDebugger)
-    , mFilename(aFilename)
-    , mLineno(aLineno)
-    , mMessage(aMessage)
-  {
-  }
-
-private:
-  ~ReportDebuggerErrorRunnable()
-  { }
-
-  NS_IMETHOD
-  Run() override
-  {
-    mDebugger->ReportErrorToDebuggerOnMainThread(mFilename, mLineno, mMessage);
-
-    return NS_OK;
-  }
-};
-
-WorkerDebugger::WorkerDebugger(WorkerPrivate* aWorkerPrivate)
-: mWorkerPrivate(aWorkerPrivate),
-  mIsInitialized(false)
-{
-  AssertIsOnMainThread();
-}
-
-WorkerDebugger::~WorkerDebugger()
-{
-  MOZ_ASSERT(!mWorkerPrivate);
-
-  if (!NS_IsMainThread()) {
-    for (size_t index = 0; index < mListeners.Length(); ++index) {
-      NS_ReleaseOnMainThreadSystemGroup(
-        "WorkerDebugger::mListeners", mListeners[index].forget());
-    }
-  }
-}
-
-NS_IMPL_ISUPPORTS(WorkerDebugger, nsIWorkerDebugger)
-
-NS_IMETHODIMP
-WorkerDebugger::GetIsClosed(bool* aResult)
-{
-  AssertIsOnMainThread();
-
-  *aResult = !mWorkerPrivate;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetIsChrome(bool* aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  *aResult = mWorkerPrivate->IsChromeWorker();
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetIsInitialized(bool* aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  *aResult = mIsInitialized;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetParent(nsIWorkerDebugger** aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  WorkerPrivate* parent = mWorkerPrivate->GetParent();
-  if (!parent) {
-    *aResult = nullptr;
-    return NS_OK;
-  }
-
-  MOZ_ASSERT(mWorkerPrivate->IsDedicatedWorker());
-
-  nsCOMPtr<nsIWorkerDebugger> debugger = parent->Debugger();
-  debugger.forget(aResult);
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetType(uint32_t* aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  *aResult = mWorkerPrivate->Type();
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetUrl(nsAString& aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  aResult = mWorkerPrivate->ScriptURL();
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetWindow(mozIDOMWindow** aResult)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  if (mWorkerPrivate->GetParent() || !mWorkerPrivate->IsDedicatedWorker()) {
-    *aResult = nullptr;
-    return NS_OK;
-  }
-
-  nsCOMPtr<nsPIDOMWindowInner> window = mWorkerPrivate->GetWindow();
-  window.forget(aResult);
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetPrincipal(nsIPrincipal** aResult)
-{
-  AssertIsOnMainThread();
-  MOZ_ASSERT(aResult);
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  nsCOMPtr<nsIPrincipal> prin = mWorkerPrivate->GetPrincipal();
-  prin.forget(aResult);
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::GetServiceWorkerID(uint32_t* aResult)
-{
-  AssertIsOnMainThread();
-  MOZ_ASSERT(aResult);
-
-  if (!mWorkerPrivate || !mWorkerPrivate->IsServiceWorker()) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  *aResult = mWorkerPrivate->ServiceWorkerID();
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::Initialize(const nsAString& aURL)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  if (!mIsInitialized) {
-    RefPtr<CompileDebuggerScriptRunnable> runnable =
-      new CompileDebuggerScriptRunnable(mWorkerPrivate, aURL);
-    if (!runnable->Dispatch()) {
-      return NS_ERROR_FAILURE;
-    }
-
-    mIsInitialized = true;
-  }
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::PostMessageMoz(const nsAString& aMessage)
-{
-  AssertIsOnMainThread();
-
-  if (!mWorkerPrivate || !mIsInitialized) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  RefPtr<DebuggerMessageEventRunnable> runnable =
-    new DebuggerMessageEventRunnable(mWorkerPrivate, aMessage);
-  if (!runnable->Dispatch()) {
-    return NS_ERROR_FAILURE;
-  }
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::AddListener(nsIWorkerDebuggerListener* aListener)
-{
-  AssertIsOnMainThread();
-
-  if (mListeners.Contains(aListener)) {
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  mListeners.AppendElement(aListener);
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-WorkerDebugger::RemoveListener(nsIWorkerDebuggerListener* aListener)
-{
-  AssertIsOnMainThread();
-
-  if (!mListeners.Contains(aListener)) {
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  mListeners.RemoveElement(aListener);
-  return NS_OK;
-}
-
-void
-WorkerDebugger::Close()
-{
-  MOZ_ASSERT(mWorkerPrivate);
-  mWorkerPrivate = nullptr;
-
-  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
-  for (size_t index = 0; index < listeners.Length(); ++index) {
-      listeners[index]->OnClose();
-  }
-}
-
-void
-WorkerDebugger::PostMessageToDebugger(const nsAString& aMessage)
-{
-  mWorkerPrivate->AssertIsOnWorkerThread();
-
-  RefPtr<PostDebuggerMessageRunnable> runnable =
-    new PostDebuggerMessageRunnable(this, aMessage);
-  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
-    NS_WARNING("Failed to post message to debugger on main thread!");
-  }
-}
-
-void
-WorkerDebugger::PostMessageToDebuggerOnMainThread(const nsAString& aMessage)
-{
-  AssertIsOnMainThread();
-
-  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
-  for (size_t index = 0; index < listeners.Length(); ++index) {
-    listeners[index]->OnMessage(aMessage);
-  }
-}
-
-void
-WorkerDebugger::ReportErrorToDebugger(const nsAString& aFilename,
-                                      uint32_t aLineno,
-                                      const nsAString& aMessage)
-{
-  mWorkerPrivate->AssertIsOnWorkerThread();
-
-  RefPtr<ReportDebuggerErrorRunnable> runnable =
-    new ReportDebuggerErrorRunnable(this, aFilename, aLineno, aMessage);
-  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
-    NS_WARNING("Failed to report error to debugger on main thread!");
-  }
-}
-
-void
-WorkerDebugger::ReportErrorToDebuggerOnMainThread(const nsAString& aFilename,
-                                                  uint32_t aLineno,
-                                                  const nsAString& aMessage)
-{
-  AssertIsOnMainThread();
-
-  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> listeners(mListeners);
-  for (size_t index = 0; index < listeners.Length(); ++index) {
-    listeners[index]->OnError(aFilename, aLineno, aMessage);
-  }
-
-  WorkerErrorReport report;
-  report.mMessage = aMessage;
-  report.mFilename = aFilename;
-  LogErrorToConsole(report, 0);
-}
-
 WorkerPrivate::WorkerPrivate(WorkerPrivate* aParent,
                              const nsAString& aScriptURL,
                              bool aIsChromeWorker, WorkerType aWorkerType,
@@ -6686,6 +6178,69 @@ EventTarget::IsOnCurrentThreadInfallible()
   return mWorkerPrivate->IsOnCurrentThread();
 }
 
+void
+LogErrorToConsole(const WorkerErrorReport& aReport, uint64_t aInnerWindowId)
+{
+  AssertIsOnMainThread();
+
+  RefPtr<nsScriptErrorBase> scriptError = new nsScriptError();
+  NS_WARNING_ASSERTION(scriptError, "Failed to create script error!");
+
+  if (scriptError) {
+    nsAutoCString category("Web Worker");
+    if (NS_FAILED(scriptError->InitWithWindowID(aReport.mMessage,
+                                                aReport.mFilename,
+                                                aReport.mLine,
+                                                aReport.mLineNumber,
+                                                aReport.mColumnNumber,
+                                                aReport.mFlags,
+                                                category,
+                                                aInnerWindowId))) {
+      NS_WARNING("Failed to init script error!");
+      scriptError = nullptr;
+    }
+
+    for (size_t i = 0, len = aReport.mNotes.Length(); i < len; i++) {
+      const WorkerErrorNote& note = aReport.mNotes.ElementAt(i);
+
+      nsScriptErrorNote* noteObject = new nsScriptErrorNote();
+      noteObject->Init(note.mMessage, note.mFilename,
+                       note.mLineNumber, note.mColumnNumber);
+      scriptError->AddNote(noteObject);
+    }
+  }
+
+  nsCOMPtr<nsIConsoleService> consoleService =
+    do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+  NS_WARNING_ASSERTION(consoleService, "Failed to get console service!");
+
+  if (consoleService) {
+    if (scriptError) {
+      if (NS_SUCCEEDED(consoleService->LogMessage(scriptError))) {
+        return;
+      }
+      NS_WARNING("LogMessage failed!");
+    } else if (NS_SUCCEEDED(consoleService->LogStringMessage(
+                              aReport.mMessage.BeginReading()))) {
+      return;
+    }
+    NS_WARNING("LogStringMessage failed!");
+  }
+
+  NS_ConvertUTF16toUTF8 msg(aReport.mMessage);
+  NS_ConvertUTF16toUTF8 filename(aReport.mFilename);
+
+  static const char kErrorString[] = "JS error in Web Worker: %s [%s:%u]";
+
+#ifdef ANDROID
+  __android_log_print(ANDROID_LOG_INFO, "Gecko", kErrorString, msg.get(),
+                      filename.get(), aReport.mLineNumber);
+#endif
+
+  fprintf(stderr, kErrorString, msg.get(), filename.get(), aReport.mLineNumber);
+  fflush(stderr);
+}
+
 BEGIN_WORKERS_NAMESPACE
 
 // Force instantiation.
diff --git a/dom/workers/WorkerPrivate.h b/dom/workers/WorkerPrivate.h
index 0c879d4e918f..8707598599e9 100644
--- a/dom/workers/WorkerPrivate.h
+++ b/dom/workers/WorkerPrivate.h
@@ -14,7 +14,6 @@
 #include "nsIContentPolicy.h"
 #include "nsIContentSecurityPolicy.h"
 #include "nsILoadGroup.h"
-#include "nsIWorkerDebugger.h"
 #include "nsPIDOMWindow.h"
 
 #include "mozilla/Assertions.h"
@@ -83,9 +82,6 @@ class PrincipalInfo;
 
 struct PRThread;
 
-class ReportDebuggerErrorRunnable;
-class PostDebuggerMessageRunnable;
-
 BEGIN_WORKERS_NAMESPACE
 
 class AutoSyncLoopHolder;
@@ -955,46 +951,6 @@ public:
   }
 };
 
-class WorkerDebugger : public nsIWorkerDebugger {
-  friend class ::ReportDebuggerErrorRunnable;
-  friend class ::PostDebuggerMessageRunnable;
-
-  WorkerPrivate* mWorkerPrivate;
-  bool mIsInitialized;
-  nsTArray<nsCOMPtr<nsIWorkerDebuggerListener>> mListeners;
-
-public:
-  explicit WorkerDebugger(WorkerPrivate* aWorkerPrivate);
-
-  NS_DECL_ISUPPORTS
-  NS_DECL_NSIWORKERDEBUGGER
-
-  void
-  AssertIsOnParentThread();
-
-  void
-  Close();
-
-  void
-  PostMessageToDebugger(const nsAString& aMessage);
-
-  void
-  ReportErrorToDebugger(const nsAString& aFilename, uint32_t aLineno,
-                        const nsAString& aMessage);
-
-private:
-  virtual
-  ~WorkerDebugger();
-
-  void
-  PostMessageToDebuggerOnMainThread(const nsAString& aMessage);
-
-  void
-  ReportErrorToDebuggerOnMainThread(const nsAString& aFilename,
-                                    uint32_t aLineno,
-                                    const nsAString& aMessage);
-};
-
 class WorkerPrivate : public WorkerPrivateParent<WorkerPrivate>
 {
   friend class WorkerHolder;
@@ -1700,6 +1656,10 @@ public:
   }
 };
 
+// TODO: this will be removed in the next patch
+void
+LogErrorToConsole(const WorkerErrorReport& aReport, uint64_t aInnerWindowId);
+
 END_WORKERS_NAMESPACE
 
 #endif /* mozilla_dom_workers_workerprivate_h__ */
diff --git a/dom/workers/WorkerRunnable.h b/dom/workers/WorkerRunnable.h
index 11132e8fd4c6..f3c4678b5ac6 100644
--- a/dom/workers/WorkerRunnable.h
+++ b/dom/workers/WorkerRunnable.h
@@ -8,6 +8,7 @@
 #define mozilla_dom_workers_workerrunnable_h__
 
 #include "WorkerCommon.h"
+#include "WorkerHolder.h"
 
 #include "nsICancelableRunnable.h"
 
diff --git a/dom/workers/moz.build b/dom/workers/moz.build
index 5951cbc8cf79..ba3213206c8d 100644
--- a/dom/workers/moz.build
+++ b/dom/workers/moz.build
@@ -20,6 +20,7 @@ EXPORTS.mozilla.dom += [
 EXPORTS.mozilla.dom.workers += [
     'RuntimeService.h',
     'WorkerCommon.h',
+    'WorkerDebugger.h',
     'WorkerDebuggerManager.h',
     'WorkerLoadInfo.h',
 ]
@@ -47,6 +48,7 @@ UNIFIED_SOURCES += [
     'RuntimeService.cpp',
     'ScriptLoader.cpp',
     'SharedWorker.cpp',
+    'WorkerDebugger.cpp',
     'WorkerDebuggerManager.cpp',
     'WorkerHolder.cpp',
     'WorkerHolderToken.cpp',