Initialize data reduction proxy bypass stats on IO thread

components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h
index db75fd5cec8ccbdbc78090e109696ee68a69ab79..b185cb307a3c83ff0dda839c8784dd06da2b7d7f 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.h
@@ -6,6 +6,7 @@
 #define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_BYPASS_PROTOCOL_H_
 
 #include "base/macros.h"
+#include "base/threading/thread_checker.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h"
 
 namespace net {
@@ -53,6 +54,8 @@ class DataReductionProxyBypassProtocol {
   // Must outlive |this|.
   DataReductionProxyConfig* config_;
 
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(DataReductionProxyBypassProtocol);
 };