Add signed_exchange_utils::ShouldAdvertiseAcceptHeader

This CL introduces signed_exchange_utils::ShouldAdvertiseAcceptHeader,
which can be used to query if a origin should be sent
"Accept: application/signed-exchange" header.

The origins list is managed by the feature "SignedHTTPExchangeAcceptHeader",
and a Finch param attached to it.

Note: Use the below args to test this:
--enable-features=SignedHTTPExchangeAcceptHeader<AcceptHeaderStudy
--force-fieldtrials=AcceptHeaderStudy/Group
--force-fieldtrial-params=AcceptHeaderStudy.Group:OriginsList/www%2eexample%2ecom

The subsequent CL will actually plumb this to the navigation loaders.

Bug: 887201
Change-Id: I06cc991e396b28ab0d02e2bbba3a117fd53d4fe5
Reviewed-on: https://chromium-review.googlesource.com/1235473
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594572}

content/browser/web_package/signed_exchange_utils.cc

@@ -5,9 +5,13 @@
 #include "content/browser/web_package/signed_exchange_utils.h"
 
 #include "base/feature_list.h"
+#include "base/metrics/field_trial_params.h"
+#include "base/no_destructor.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
+#include "content/browser/web_package/origins_list.h"
 #include "content/browser/web_package/signed_exchange_devtools_proxy.h"
 #include "content/browser/web_package/signed_exchange_error.h"
 #include "content/browser/web_package/signed_exchange_request_handler.h"
@@ -30,6 +34,31 @@ void ReportErrorAndTraceEvent(
     devtools_proxy->ReportError(error_message, std::move(error_field));
 }
 
+namespace {
+
+OriginsList CreateAdvertiseAcceptHeaderOriginsList() {
+  std::string param = base::GetFieldTrialParamValueByFeature(
+      features::kSignedHTTPExchangeAcceptHeader,
+      features::kSignedHTTPExchangeAcceptHeaderFieldTrialParamName);
+  if (param.empty())
+    DLOG(ERROR) << "The Accept-SXG origins list param is empty.";
+
+  return OriginsList(param);
+}
+
+}  //  namespace
+
+bool ShouldAdvertiseAcceptHeader(const url::Origin& origin) {
+  if (!base::FeatureList::IsEnabled(features::kSignedHTTPExchangeAcceptHeader))
+    return false;
+
+  // |origins_list| is initialized in a thread-safe manner.
+  // Querying OriginsList::Match() should be safe since it's read-only access.
+  static base::NoDestructor<OriginsList> origins_list(
+      CreateAdvertiseAcceptHeaderOriginsList());
+  return origins_list->Match(origin);
+}
+
 bool IsSignedExchangeHandlingEnabled() {
   return base::FeatureList::IsEnabled(features::kSignedHTTPExchange) ||
          base::FeatureList::IsEnabled(features::kSignedHTTPExchangeOriginTrial);

content/browser/web_package/signed_exchange_utils.h

@@ -8,12 +8,17 @@
 #include <string>
 
 #include "base/optional.h"
+#include "content/browser/web_package/origins_list.h"
 #include "content/browser/web_package/signed_exchange_consts.h"
 #include "content/browser/web_package/signed_exchange_error.h"
 #include "content/common/content_export.h"
 
 class GURL;
 
+namespace url {
+class Origin;
+}  // namespace url
+
 namespace network {
 struct ResourceResponseHead;
 }  // namespace network
@@ -33,6 +38,10 @@ void ReportErrorAndTraceEvent(
     base::Optional<SignedExchangeError::FieldIndexPair> error_field =
         base::nullopt);
 
+// Returns true if Accept headers should be sent with
+// "application/signed-exchange".
+bool ShouldAdvertiseAcceptHeader(const url::Origin& origin);
+
 // Returns true when SignedHTTPExchange feature or SignedHTTPExchangeOriginTrial
 // feature is enabled.
 bool IsSignedExchangeHandlingEnabled();

content/public/common/content_features.cc

@@ -413,6 +413,13 @@ const base::Feature kSharedArrayBuffer {
 const base::Feature kSignedHTTPExchange{"SignedHTTPExchange",
                                         base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Send "Accept: application/signed-exchange" header to origins who opt-in.
+const base::Feature kSignedHTTPExchangeAcceptHeader{
+    "SignedHTTPExchangeAcceptHeader", base::FEATURE_DISABLED_BY_DEFAULT};
+// Field trial parameter containing the list of origins that opted-in to receive
+// "Accept: application/signed-exchange" header.
+const char kSignedHTTPExchangeAcceptHeaderFieldTrialParamName[] = "OriginsList";
+
 // Origin Trial of Origin-Signed HTTP Exchanges (for WebPackage Loading)
 const base::Feature kSignedHTTPExchangeOriginTrial{
     "SignedHTTPExchangeOriginTrial", base::FEATURE_DISABLED_BY_DEFAULT};

content/public/common/content_features.h

@@ -98,6 +98,9 @@ CONTENT_EXPORT extern const base::Feature kServiceWorkerPaymentApps;
 CONTENT_EXPORT extern const base::Feature kServiceWorkerScriptFullCodeCache;
 CONTENT_EXPORT extern const base::Feature kSharedArrayBuffer;
 CONTENT_EXPORT extern const base::Feature kSignedHTTPExchange;
+CONTENT_EXPORT extern const base::Feature kSignedHTTPExchangeAcceptHeader;
+CONTENT_EXPORT extern const char
+    kSignedHTTPExchangeAcceptHeaderFieldTrialParamName[];
 CONTENT_EXPORT extern const base::Feature kSignedHTTPExchangeOriginTrial;
 CONTENT_EXPORT extern const base::Feature kSpareRendererForSitePerProcess;
 CONTENT_EXPORT extern const base::Feature kTimerThrottlingForHiddenFrames;