Refactor OriginTrialPolicy to be an abstract interface in content/public/common

content/public/common/content_client.cc

Index: content/public/common/content_client.cc
diff --git a/content/public/common/content_client.cc b/content/public/common/content_client.cc
index 739af1857117670b029a8dd828b352c8de40bac6..202a828a98eba51714b6f66ae88bd44d25c03944 100644
--- a/content/public/common/content_client.cc
+++ b/content/public/common/content_client.cc
@@ -121,13 +121,8 @@ bool ContentClient::IsSupplementarySiteIsolationModeEnabled() {
 
 void ContentClient::InitializeOriginTrialPolicy() {}
 
-base::StringPiece ContentClient::GetOriginTrialPublicKey() const {
-  return base::StringPiece();
-}
-
-bool ContentClient::IsOriginTrialFeatureDisabled(
-    base::StringPiece feature) const {
-  return false;
+const OriginTrialPolicy* ContentClient::GetOriginTrialPolicy() const {
+  return nullptr;
 }
 
 bool ContentClient::AllowScriptExtensionForServiceWorker(