Initialize debugger together with isolate.

third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp

Index: third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp b/third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp
index 236efc7c59ded1d1793537074c2dd098036bbd23..de1987b17456bdd644d9fbabaa16dc02b86e4a7b 100644
--- a/third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/WindowProxy.cpp
@@ -110,7 +110,7 @@ void WindowProxy::disposeContext(GlobalDetachmentBehavior behavior)
         LocalFrame* frame = toLocalFrame(m_frame);
         // The embedder could run arbitrary code in response to the willReleaseScriptContext callback, so all disposing should happen after it returns.
         frame->loader().client()->willReleaseScriptContext(context, m_world->worldId());
-        MainThreadDebugger::contextWillBeDestroyed(m_scriptState.get());
+        MainThreadDebugger::instance()->contextWillBeDestroyed(m_scriptState.get());
     }
 
     m_document.clear();
@@ -269,7 +269,7 @@ bool WindowProxy::initialize()
     }
     if (m_frame->isLocalFrame()) {
         LocalFrame* frame = toLocalFrame(m_frame);
-        MainThreadDebugger::contextCreated(m_scriptState.get(), frame, origin);
+        MainThreadDebugger::instance()->contextCreated(m_scriptState.get(), frame, origin);
         frame->loader().client()->didCreateScriptContext(context, m_world->extensionGroup(), m_world->worldId());
     }
     return true;