Add support to previews/ for Server LoFi and LitePages

components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc

Index: components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
index ac08fb10e9dd25abf5e23f677714624275d659ce..5e3cd12f13414510cf584f57c1cb057cd304e8ac 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
@@ -59,6 +59,9 @@ const char kPingbackURL[] =
 const char kServerExperimentsFieldTrial[] =
     "DataReductionProxyServerExperiments";
 
+// LitePage black list version.
+const char kLitePageBlacklistVersion[] = "lite-page-blacklist-version";
+
 bool IsIncludedInFieldTrial(const std::string& name) {
   return base::StartsWith(FieldTrialList::FindFullName(name), kEnabled,
                           base::CompareCase::SENSITIVE);
@@ -313,6 +316,12 @@ bool ShouldForceEnableDataReductionProxy() {
       data_reduction_proxy::switches::kEnableDataReductionProxy);
 }
 
+int LitePageVersion() {
+  return GetFieldTrialParameterAsInteger(
+      data_reduction_proxy::params::GetLoFiFieldTrialName(),
+      kLitePageBlacklistVersion, 0, 0);
+}
+
 int GetFieldTrialParameterAsInteger(const std::string& group,
                                     const std::string& param_name,
                                     int default_value,