Oilpan: move WebDevToolsFrontend to the heap.

Source/web/WebDevToolsFrontendImpl.h

Index: Source/web/WebDevToolsFrontendImpl.h
diff --git a/Source/web/WebDevToolsFrontendImpl.h b/Source/web/WebDevToolsFrontendImpl.h
index 7a441f7f89422b47109c286201c7d3bd0d3d120c..530f20667246a4fe0d9333fb8f8066d0ba26e4bf 100644
--- a/Source/web/WebDevToolsFrontendImpl.h
+++ b/Source/web/WebDevToolsFrontendImpl.h
@@ -43,7 +43,7 @@ namespace blink {
 class DevToolsHost;
 class WebLocalFrameImpl;
 
-class WebDevToolsFrontendImpl final : public WebDevToolsFrontend, public InspectorFrontendClient {
+class WebDevToolsFrontendImpl : public RefCountedWillBeGarbageCollectedFinalized<WebDevToolsFrontendImpl>, public InspectorFrontendClient {
     WTF_MAKE_NONCOPYABLE(WebDevToolsFrontendImpl);
 public:
     WebDevToolsFrontendImpl(WebLocalFrameImpl*, WebDevToolsFrontendClient*);
@@ -51,9 +51,9 @@ public:
 
     void didClearWindowObject(WebLocalFrameImpl*);
 
-    void sendMessageToBackend(const WTF::String&) override;
+    void sendMessageToBackend(const String&) override;
 
-    void sendMessageToEmbedder(const WTF::String&) override;
+    void sendMessageToEmbedder(const String&) override;
 
     bool isUnderTest() override;
 
@@ -61,14 +61,18 @@ public:
 
     void setInjectedScriptForOrigin(const String& origin, const String& source) override;
 
+    DECLARE_TRACE();
+
 private:
-    WebLocalFrameImpl* m_webFrame;
+
+    RawPtrWillBeMember<WebLocalFrameImpl> m_webFrame;
     WebDevToolsFrontendClient* m_client;
-    RefPtrWillBePersistent<DevToolsHost> m_devtoolsHost;
-    typedef HashMap<String, String> InjectedScriptForOriginMap;
+    RefPtrWillBeMember<DevToolsHost> m_devtoolsHost;
+
+    using InjectedScriptForOriginMap = HashMap<String, String>;
     InjectedScriptForOriginMap m_injectedScriptForOrigin;
 };
 
 } // namespace blink
 
-#endif
+#endif // WebDevToolsFrontendImpl_h