Move dart_debugger into tonic and use it in mojo dart controller

tonic/dart_debugger.cc

Index: tonic/dart_debugger.cc
diff --git a/mojo/dart/embedder/dart_debugger.cc b/tonic/dart_debugger.cc
similarity index 97%
rename from mojo/dart/embedder/dart_debugger.cc
rename to tonic/dart_debugger.cc
index dab8264f49d494fb740fa810211861bafc80b1de..44de8ce75b982d31cc3f36a12e8696de91b8eb30 100644
--- a/mojo/dart/embedder/dart_debugger.cc
+++ b/tonic/dart_debugger.cc
@@ -2,14 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "mojo/dart/embedder/dart_debugger.h"
+#include "tonic/dart_debugger.h"
+
 #include "dart/runtime/include/dart_api.h"
 #include "dart/runtime/include/dart_native_api.h"
 #include "dart/runtime/include/dart_tools_api.h"
 
 
-namespace mojo {
-namespace dart {
+namespace tonic {
+
+MonitorLocker::~MonitorLocker() {
+  monitor_->Exit();
+}
 
 void DartDebuggerIsolate::MessageLoop() {
   MonitorLocker ml(&monitor_);
@@ -135,5 +139,4 @@ base::Lock* DartDebugger::lock_ = nullptr;
 std::vector<std::unique_ptr<DartDebuggerIsolate>>* DartDebugger::isolates_ =
     nullptr;
 
-}  // namespace dart
-}  // namespace mojo
+}  // namespace tonic