Make Foreign Fetch an origin trial.

content/browser/storage_partition_impl_map.cc

Index: content/browser/storage_partition_impl_map.cc
diff --git a/content/browser/storage_partition_impl_map.cc b/content/browser/storage_partition_impl_map.cc
index ae72484baa8bb20a79a4d7abe761e0ea4461db46..7c37c608ae53232f57ab2c343986f245d6f79b5b 100644
--- a/content/browser/storage_partition_impl_map.cc
+++ b/content/browser/storage_partition_impl_map.cc
@@ -42,6 +42,7 @@
 #include "content/public/browser/storage_partition.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
+#include "content/public/common/origin_trial_policy.h"
 #include "content/public/common/url_constants.h"
 #include "crypto/sha2.h"
 #include "net/url_request/url_request_context.h"
@@ -445,8 +446,12 @@ StoragePartitionImpl* StoragePartitionImplMap::Get(
   request_interceptors.push_back(
       ServiceWorkerRequestHandler::CreateInterceptor(
           browser_context_->GetResourceContext()).release());
+  OriginTrialPolicy* origin_trial_policy =
+      GetContentClient()->GetOriginTrialPolicy();
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableExperimentalWebPlatformFeatures)) {
+          switches::kEnableExperimentalWebPlatformFeatures) ||
+      !origin_trial_policy ||
+      !origin_trial_policy->IsFeatureDisabled("ForeignFetch")) {
     request_interceptors.push_back(
         ForeignFetchRequestHandler::CreateInterceptor(
             browser_context_->GetResourceContext())