DevTools: simplify http handler delegate as it is moving into content.

chromecast/browser/devtools/cast_dev_tools_delegate.cc

Index: chromecast/browser/devtools/cast_dev_tools_delegate.cc
diff --git a/chromecast/browser/devtools/cast_dev_tools_delegate.cc b/chromecast/browser/devtools/cast_dev_tools_delegate.cc
index 53d9b985e2800aa59ada7bb6f3f0872d01528df5..0e80eb55832b1288966797cde797dc553b6894c8 100644
--- a/chromecast/browser/devtools/cast_dev_tools_delegate.cc
+++ b/chromecast/browser/devtools/cast_dev_tools_delegate.cc
@@ -34,14 +34,5 @@ std::string CastDevToolsDelegate::GetFrontendResource(
   return std::string();
 }
 
-std::string CastDevToolsDelegate::GetPageThumbnailData(const GURL& url) {
-  return std::string();
-}
-
-content::DevToolsExternalAgentProxyDelegate*
-CastDevToolsDelegate::HandleWebSocketConnection(const std::string& path) {
-  return nullptr;
-}
-
 }  // namespace shell
 }  // namespace chromecast