Generate four types of X-Client-Data headers and store them in a map.

The status quo implementation generates two types,
cached_variation_ids_header_signed_in_ and cached_variation_ids_header_,
which are stored in strings.

In order to limit the number of VariationIDs included in the header in
third-party contexts, four headers are needed. The headers are stored in
a map.

FYI: While GetClientDataHeader()'s |web_visibility| argument is only
Study_GoogleWebVisibility_ANY for the time being, this will not always
be the case.

This change paves the way for limiting the set of experiment IDs
included in X-Client-Data headers sent in third-party contexts.

Bug: 1094303
Change-Id: Ifdc502fbc25fc3b09911414198022e059132a83c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388763Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#807875}

chrome/browser/BUILD.gn

@@ -2151,6 +2151,7 @@ static_library("browser") {
     "//components/variations",
     "//components/variations/field_trial_config",
     "//components/variations/net",
+    "//components/variations/proto",
     "//components/variations/service",
     "//components/vector_icons",
     "//components/version_info",

chrome/browser/net/variations_http_headers_browsertest.cc

@@ -35,6 +35,7 @@
 #include "components/optimization_guide/proto/hints.pb.h"
 #include "components/signin/public/identity_manager/identity_test_utils.h"
 #include "components/variations/net/variations_http_headers.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/variations_ids_provider.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/storage_partition.h"
@@ -381,10 +382,19 @@ void CreateGoogleSignedInFieldTrial() {
   scoped_refptr<base::FieldTrial> trial_1(CreateTrialAndAssociateId(
       "t1", default_name, variations::GOOGLE_WEB_PROPERTIES_SIGNED_IN, 123));
 
-  auto* variations_ids_provider =
-      variations::VariationsIdsProvider::GetInstance();
-  EXPECT_NE(variations_ids_provider->GetClientDataHeader(true),
-            variations_ids_provider->GetClientDataHeader(false));
+  auto* provider = variations::VariationsIdsProvider::GetInstance();
+
+  EXPECT_NE(
+      provider->GetClientDataHeader(
+          /*is_signed_in=*/true, variations::Study_GoogleWebVisibility_ANY),
+      provider->GetClientDataHeader(
+          /*is_signed_in=*/false, variations::Study_GoogleWebVisibility_ANY));
+  EXPECT_NE(provider->GetClientDataHeader(
+                /*is_signed_in=*/true,
+                variations::Study_GoogleWebVisibility_FIRST_PARTY),
+            provider->GetClientDataHeader(
+                /*is_signed_in=*/false,
+                variations::Study_GoogleWebVisibility_FIRST_PARTY));
 }
 
 }  // namespace
@@ -439,8 +449,10 @@ IN_PROC_BROWSER_TEST_F(VariationsHttpHeadersBrowserTest, UserSignedIn) {
   base::Optional<std::string> header =
       GetReceivedHeader(GetGoogleUrl(), "X-Client-Data");
   ASSERT_TRUE(header);
-  EXPECT_EQ(*header, variations::VariationsIdsProvider::GetInstance()
-                         ->GetClientDataHeader(true));
+  EXPECT_EQ(
+      *header,
+      variations::VariationsIdsProvider::GetInstance()->GetClientDataHeader(
+          /*is_signed_in=*/true, variations::Study_GoogleWebVisibility_ANY));
 }
 
 IN_PROC_BROWSER_TEST_F(VariationsHttpHeadersBrowserTest, UserNotSignedIn) {
@@ -454,8 +466,10 @@ IN_PROC_BROWSER_TEST_F(VariationsHttpHeadersBrowserTest, UserNotSignedIn) {
   base::Optional<std::string> header =
       GetReceivedHeader(GetGoogleUrl(), "X-Client-Data");
   ASSERT_TRUE(header);
-  EXPECT_EQ(*header, variations::VariationsIdsProvider::GetInstance()
-                         ->GetClientDataHeader(false));
+  EXPECT_EQ(
+      *header,
+      variations::VariationsIdsProvider::GetInstance()->GetClientDataHeader(
+          /*is_signed_in=*/false, variations::Study_GoogleWebVisibility_ANY));
 }
 
 IN_PROC_BROWSER_TEST_F(

chrome/browser/profiles/profile.cc

@@ -29,6 +29,7 @@
 #include "components/sync/base/sync_prefs.h"
 #include "components/sync/driver/sync_driver_switches.h"
 #include "components/sync/driver/sync_service.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/variations_client.h"
 #include "components/variations/variations_ids_provider.h"
 #include "content/public/browser/notification_service.h"
@@ -92,9 +93,13 @@ class ChromeVariationsClient : public variations::VariationsClient {
     return browser_context_->IsOffTheRecord();
   }
 
+  // TODO(crbug/1094303): Update the signature to accept a
+  // variations::Study_GoogleWebVisibility and pass the given value to
+  // GetClientDataHeader().
   std::string GetVariationsHeader() const override {
     return variations::VariationsIdsProvider::GetInstance()
-        ->GetClientDataHeader(IsSignedIn());
+        ->GetClientDataHeader(IsSignedIn(),
+                              variations::Study_GoogleWebVisibility_ANY);
   }
 
  private:

components/variations/net/variations_http_headers.cc

@@ -16,6 +16,7 @@
 #include "base/strings/string_util.h"
 #include "components/google/core/common/google_util.h"
 #include "components/variations/net/omnibox_http_headers.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/variations_ids_provider.h"
 #include "net/base/isolation_info.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
@@ -234,9 +235,12 @@ class VariationsHeaderHelper {
   }
 
  private:
+  // TODO(crbug/1094303): Update the signature to accept a
+  // Study_GoogleWebVisibility and pass the given value to
+  // GetClientDataHeader().
   static std::string CreateVariationsHeader(SignedIn signed_in) {
     return VariationsIdsProvider::GetInstance()->GetClientDataHeader(
-        signed_in == SignedIn::kYes);
+        signed_in == SignedIn::kYes, Study_GoogleWebVisibility_ANY);
   }
 
   network::ResourceRequest* resource_request_;

components/variations/net/variations_url_loader_throttle.cc

@@ -47,6 +47,8 @@ void VariationsURLLoaderThrottle::AppendThrottleIfNeeded(
   if (!variations_client || variations_client->IsOffTheRecord())
     return;
 
+  // TODO(crbug/1094303): Consider both variations::Study_GoogleWebVisibility
+  // values.
   throttles->push_back(std::make_unique<VariationsURLLoaderThrottle>(
       variations_client->GetVariationsHeader()));
 }

components/variations/variations_client.h

@@ -20,6 +20,8 @@ class VariationsClient {
   virtual bool IsOffTheRecord() const = 0;
 
   // Returns the variations header that should be appended for google requests.
+  // TODO(crbug/1094303): Update the signature to take a
+  // variations::Study_GoogleWebVisibility.
   virtual std::string GetVariationsHeader() const = 0;
 };
 

components/variations/variations_ids_provider.cc

@@ -4,8 +4,6 @@
 
 #include "components/variations/variations_ids_provider.h"
 
-#include <stddef.h>
-
 #include <algorithm>
 
 #include "base/base64.h"
@@ -19,6 +17,12 @@
 
 namespace variations {
 
+bool VariationsHeaderKey::operator<(const VariationsHeaderKey& other) const {
+  if (is_signed_in != other.is_signed_in)
+    return is_signed_in < other.is_signed_in;
+  return web_visibility < other.web_visibility;
+}
+
 // Adding/removing headers is implemented by request consumers, and how it is
 // implemented depends on the request type.
 // There are three cases:
@@ -37,17 +41,20 @@ VariationsIdsProvider* VariationsIdsProvider::GetInstance() {
   return base::Singleton<VariationsIdsProvider>::get();
 }
 
-std::string VariationsIdsProvider::GetClientDataHeader(bool is_signed_in) {
+std::string VariationsIdsProvider::GetClientDataHeader(
+    bool is_signed_in,
+    Study_GoogleWebVisibility web_visibility) {
   // Lazily initialize the header, if not already done, before attempting to
   // transmit it.
   InitVariationIDsCacheIfNeeded();
 
   std::string variation_ids_header_copy;
   {
-    base::AutoLock scoped_lock(lock_);
-    variation_ids_header_copy = is_signed_in
-                                    ? cached_variation_ids_header_signed_in_
-                                    : cached_variation_ids_header_;
+    auto it = variations_headers_map_.find(
+        VariationsHeaderKey{is_signed_in, web_visibility});
+    if (it == variations_headers_map_.end())
+      return "";
+    variation_ids_header_copy = it->second;
   }
   return variation_ids_header_copy;
 }
@@ -149,8 +156,7 @@ void VariationsIdsProvider::ResetForTesting() {
   default_variation_ids_set_.clear();
   synthetic_variation_ids_set_.clear();
   force_disabled_ids_set_.clear();
-  cached_variation_ids_header_.clear();
-  cached_variation_ids_header_signed_in_.clear();
+  variations_headers_map_.clear();
 }
 
 VariationsIdsProvider::VariationsIdsProvider()
@@ -228,17 +234,30 @@ void VariationsIdsProvider::CacheVariationsId(const std::string& trial_name,
 void VariationsIdsProvider::UpdateVariationIDsHeaderValue() {
   lock_.AssertAcquired();
 
-  // The header value is a serialized protobuffer of Variation IDs which is
-  // base64 encoded before transmitting as a string.
-  cached_variation_ids_header_.clear();
-  cached_variation_ids_header_signed_in_.clear();
+  variations_headers_map_.clear();
 
-  // If successful, swap the header value with the new one.
   // Note that the list of IDs and the header could be temporarily out of sync
   // if IDs are added as the header is recreated. The receiving servers are OK
   // with such discrepancies.
-  cached_variation_ids_header_ = GenerateBase64EncodedProto(false);
-  cached_variation_ids_header_signed_in_ = GenerateBase64EncodedProto(true);
+  variations_headers_map_[VariationsHeaderKey{/*is_signed_in=*/false,
+                                              Study_GoogleWebVisibility_ANY}] =
+      GenerateBase64EncodedProto(/*is_signed_in=*/false,
+                                 /*is_first_party_context=*/false);
+
+  variations_headers_map_[VariationsHeaderKey{
+      /*is_signed_in=*/false, Study_GoogleWebVisibility_FIRST_PARTY}] =
+      GenerateBase64EncodedProto(/*is_signed_in=*/false,
+                                 /*is_first_party_context=*/true);
+
+  variations_headers_map_[VariationsHeaderKey{/*is_signed_in=*/true,
+                                              Study_GoogleWebVisibility_ANY}] =
+      GenerateBase64EncodedProto(/*is_signed_in=*/true,
+                                 /*is_first_party_context=*/false);
+
+  variations_headers_map_[VariationsHeaderKey{
+      /*is_signed_in=*/true, Study_GoogleWebVisibility_FIRST_PARTY}] =
+      GenerateBase64EncodedProto(/*is_signed_in=*/true,
+                                 /*is_first_party_context=*/true);
 
   for (auto& observer : observer_list_) {
     observer.VariationIdsHeaderUpdated();
@@ -246,7 +265,8 @@ void VariationsIdsProvider::UpdateVariationIDsHeaderValue() {
 }
 
 std::string VariationsIdsProvider::GenerateBase64EncodedProto(
-    bool is_signed_in) {
+    bool is_signed_in,
+    bool is_first_party_context) {
   std::set<VariationIDEntry> all_variation_ids_set = GetAllVariationIds();
 
   ClientVariations proto;
@@ -262,15 +282,14 @@ std::string VariationsIdsProvider::GenerateBase64EncodedProto(
       case GOOGLE_WEB_PROPERTIES_FIRST_PARTY:
         if (base::FeatureList::IsEnabled(
                 internal::kRestrictGoogleWebVisibility)) {
-          // TODO(crbug/1094303): Send fewer VariationIDs in third-party
-          // contexts by excluding IDs associated with
-          // GOOGLE_WEB_PROPERTIES_FIRST_PARTY.
-          break;
+          if (is_first_party_context)
+            proto.add_variation_id(entry.first);
+        } else {
+          // When the feature is not enabled, treat VariationIDs associated with
+          // GOOGLE_WEB_PROPERTIES_FIRST_PARTY in the same way as those
+          // associated with GOOGLE_WEB_PROPERTIES_ANY_CONTEXT.
+          proto.add_variation_id(entry.first);
         }
-        // When the feature is not enabled, treat VariationIDs associated with
-        // GOOGLE_WEB_PROPERTIES_FIRST_PARTY in the same way as those
-        // associated with GOOGLE_WEB_PROPERTIES_ANY_CONTEXT.
-        proto.add_variation_id(entry.first);
         break;
       case GOOGLE_WEB_PROPERTIES_TRIGGER_ANY_CONTEXT:
         proto.add_trigger_variation_id(entry.first);
@@ -278,15 +297,14 @@ std::string VariationsIdsProvider::GenerateBase64EncodedProto(
       case GOOGLE_WEB_PROPERTIES_TRIGGER_FIRST_PARTY:
         if (base::FeatureList::IsEnabled(
                 internal::kRestrictGoogleWebVisibility)) {
-          // TODO(crbug/1094303): Send fewer VariationIDs in third-party
-          // contexts by excluding IDs associated with
-          // GOOGLE_WEB_PROPERTIES_FIRST_PARTY.
-          break;
+          if (is_first_party_context)
+            proto.add_trigger_variation_id(entry.first);
+        } else {
+          // When the feature is not enabled, treat VariationIDs associated with
+          // GOOGLE_WEB_PROPERTIES_TRIGGER_FIRST_PARTY in the same way as those
+          // associated with GOOGLE_WEB_PROPERTIES_TRIGGER_ANY_CONTEXT.
+          proto.add_trigger_variation_id(entry.first);
         }
-        // When the feature is not enabled, treat VariationIDs associated with
-        // GOOGLE_WEB_PROPERTIES_TRIGGER_FIRST_PARTY in the same way as those
-        // associated with GOOGLE_WEB_PROPERTIES_TRIGGER_ANY_CONTEXT.
-        proto.add_trigger_variation_id(entry.first);
         break;
       case GOOGLE_APP:
         // These IDs should not be added into Google Web headers.

components/variations/variations_ids_provider.h

@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_VARIATIONS_VARIATIONS_IDS_PROVIDER_H_
 #define COMPONENTS_VARIATIONS_VARIATIONS_IDS_PROVIDER_H_
 
+#include <map>
 #include <set>
 #include <string>
 #include <utility>
@@ -15,6 +16,7 @@
 #include "base/metrics/field_trial.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/synthetic_trials.h"
 #include "components/variations/variations_associated_data.h"
 
@@ -26,6 +28,21 @@ struct DefaultSingletonTraits;
 namespace variations {
 class VariationsClient;
 
+// The key for a VariationsIdsProvider's |variations_headers_map_|. A
+// VariationsHeaderKey provides more details about the VariationsIDs included in
+// a particular header. For example, the header associated with a key with true
+// for |is_signed_in| and Study_GoogleWebVisibility_ANY for |web_visibility| has
+// (i) VariationsIDs associated with external experiments, which can be sent
+// only for signed-in users and (ii) VariationsIDs that can be sent in first-
+// and third-party contexts.
+struct VariationsHeaderKey {
+  bool is_signed_in;
+  Study_GoogleWebVisibility web_visibility;
+
+  // This allows the struct to be used as a key in a map.
+  bool operator<(const VariationsHeaderKey& other) const;
+};
+
 // A helper class for maintaining client experiments and metrics state
 // transmitted in custom HTTP request headers.
 // This class is a thread-safe singleton.
@@ -43,11 +60,15 @@ class VariationsIdsProvider : public base::FieldTrialList::Observer,
 
   static VariationsIdsProvider* GetInstance();
 
-  // Returns the value of the client data header, computing and caching it if
-  // necessary. If |is_signed_in| is false, variation ids that should only be
-  // sent for signed in users (i.e. GOOGLE_WEB_PROPERTIES_SIGNED_IN entries)
-  // will not be included.
-  std::string GetClientDataHeader(bool is_signed_in);
+  // Returns the value of the X-Client-Data header corresponding to
+  // |is_signed_in| and |web_visibility|, computing and caching the header if
+  // necessary. If |is_signed_in| is false, VariationIDs that should be sent for
+  // only signed in users (i.e. GOOGLE_WEB_PROPERTIES_SIGNED_IN entries) are not
+  // included. Considering |web_visibility| allows fewer VariationIDs to be sent
+  // in third-party contexts. See IsFirstPartyContext() in
+  // variations_http_headers.cc for more details.
+  std::string GetClientDataHeader(bool is_signed_in,
+                                  Study_GoogleWebVisibility web_visibility);
 
   // Returns a space-separated string containing the list of current active
   // variations (as would be reported in the |variation_id| repeated field of
@@ -160,9 +181,10 @@ class VariationsIdsProvider : public base::FieldTrialList::Observer,
   // held.
   void UpdateVariationIDsHeaderValue();
 
-  // Generates a base64-encoded proto to be used as a header value for the given
-  // |is_signed_in| state.
-  std::string GenerateBase64EncodedProto(bool is_signed_in);
+  // Generates a base64-encoded ClientVariations proto to be used as a header
+  // value for the given |is_signed_in| and |is_first_party_context| states.
+  std::string GenerateBase64EncodedProto(bool is_signed_in,
+                                         bool is_first_party_context);
 
   // Adds variation ids and trigger variation ids to |target_set|.
   static bool AddVariationIdsToSet(
@@ -203,8 +225,14 @@ class VariationsIdsProvider : public base::FieldTrialList::Observer,
   // Provides the google experiment ids that are force-disabled by command line.
   std::set<VariationIDEntry> force_disabled_ids_set_;
 
-  std::string cached_variation_ids_header_;
-  std::string cached_variation_ids_header_signed_in_;
+  // A collection of variations headers. Each header is a base64-encoded
+  // ClientVariations proto containing VariationIDs that may be sent to Google
+  // web properties. For more details about when this may be sent, see
+  // AppendHeaderIfNeeded() in variations_http_headers.cc.
+  //
+  // The key for each header describes the VariationIDs included in its
+  // associated header. See VariationsHeaderKey's comments for more information.
+  std::map<VariationsHeaderKey, std::string> variations_headers_map_;
 
   // List of observers to notify on variation ids header update.
   // NOTE this should really check observers are unregistered but due to

components/variations/variations_ids_provider_unittest.cc

@@ -12,6 +12,7 @@
 #include "base/test/task_environment.h"
 #include "components/variations/entropy_provider.h"
 #include "components/variations/proto/client_variations.pb.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/variations_associated_data.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -75,7 +76,8 @@ TEST_F(VariationsIdsProviderTest, ForceVariationIds_Valid) {
   EXPECT_EQ(VariationsIdsProvider::ForceIdsResult::SUCCESS,
             provider.ForceVariationIds({"12", "456", "t789"}, ""));
   provider.InitVariationIDsCacheIfNeeded();
-  std::string variations = provider.GetClientDataHeader(false);
+  std::string variations = provider.GetClientDataHeader(
+      /*is_signed_in=*/false, Study_GoogleWebVisibility_ANY);
   EXPECT_FALSE(variations.empty());
   std::set<VariationID> variation_ids;
   std::set<VariationID> trigger_ids;
@@ -93,7 +95,8 @@ TEST_F(VariationsIdsProviderTest, ForceVariationIds_ValidCommandLine) {
   EXPECT_EQ(VariationsIdsProvider::ForceIdsResult::SUCCESS,
             provider.ForceVariationIds({"12"}, "456,t789"));
   provider.InitVariationIDsCacheIfNeeded();
-  std::string variations = provider.GetClientDataHeader(false);
+  std::string variations = provider.GetClientDataHeader(
+      /*is_signed_in=*/false, Study_GoogleWebVisibility_ANY);
   EXPECT_FALSE(variations.empty());
   std::set<VariationID> variation_ids;
   std::set<VariationID> trigger_ids;
@@ -111,19 +114,28 @@ TEST_F(VariationsIdsProviderTest, ForceVariationIds_Invalid) {
   EXPECT_EQ(VariationsIdsProvider::ForceIdsResult::INVALID_VECTOR_ENTRY,
             provider.ForceVariationIds({"abcd12", "456"}, ""));
   provider.InitVariationIDsCacheIfNeeded();
-  EXPECT_TRUE(provider.GetClientDataHeader(false).empty());
+  EXPECT_TRUE(provider
+                  .GetClientDataHeader(/*is_signed_in=*/false,
+                                       Study_GoogleWebVisibility_ANY)
+                  .empty());
 
   // Invalid trigger experiment id
   EXPECT_EQ(VariationsIdsProvider::ForceIdsResult::INVALID_VECTOR_ENTRY,
             provider.ForceVariationIds({"12", "tabc456"}, ""));
   provider.InitVariationIDsCacheIfNeeded();
-  EXPECT_TRUE(provider.GetClientDataHeader(false).empty());
+  EXPECT_TRUE(provider
+                  .GetClientDataHeader(/*is_signed_in=*/false,
+                                       Study_GoogleWebVisibility_ANY)
+                  .empty());
 
   // Invalid command-line ids.
   EXPECT_EQ(VariationsIdsProvider::ForceIdsResult::INVALID_SWITCH_ENTRY,
             provider.ForceVariationIds({"12", "50"}, "tabc456"));
   provider.InitVariationIDsCacheIfNeeded();
-  EXPECT_TRUE(provider.GetClientDataHeader(false).empty());
+  EXPECT_TRUE(provider
+                  .GetClientDataHeader(/*is_signed_in=*/false,
+                                       Study_GoogleWebVisibility_ANY)
+                  .empty());
 }
 
 TEST_F(VariationsIdsProviderTest, ForceDisableVariationIds_ValidCommandLine) {
@@ -134,7 +146,8 @@ TEST_F(VariationsIdsProviderTest, ForceDisableVariationIds_ValidCommandLine) {
             provider.ForceVariationIds({"1", "2", "t3", "t4"}, "5,6,t7,t8"));
   EXPECT_TRUE(provider.ForceDisableVariationIds("2,t4,6,t8"));
   provider.InitVariationIDsCacheIfNeeded();
-  std::string variations = provider.GetClientDataHeader(false);
+  std::string variations = provider.GetClientDataHeader(
+      /*is_signed_in=*/false, Study_GoogleWebVisibility_ANY);
   EXPECT_FALSE(variations.empty());
   std::set<VariationID> variation_ids;
   std::set<VariationID> trigger_ids;
@@ -156,7 +169,10 @@ TEST_F(VariationsIdsProviderTest, ForceDisableVariationIds_Invalid) {
   EXPECT_FALSE(provider.ForceDisableVariationIds("abc"));
   EXPECT_FALSE(provider.ForceDisableVariationIds("tabc456"));
   provider.InitVariationIDsCacheIfNeeded();
-  EXPECT_TRUE(provider.GetClientDataHeader(false).empty());
+  EXPECT_TRUE(provider
+                  .GetClientDataHeader(/*is_signed_in=*/false,
+                                       Study_GoogleWebVisibility_ANY)
+                  .empty());
 }
 
 TEST_F(VariationsIdsProviderTest, OnFieldTrialGroupFinalized) {
@@ -190,7 +206,8 @@ TEST_F(VariationsIdsProviderTest, OnFieldTrialGroupFinalized) {
 
   // Get non-signed in ids.
   {
-    std::string variations = provider.GetClientDataHeader(false);
+    std::string variations = provider.GetClientDataHeader(
+        /*is_signed_in=*/false, Study_GoogleWebVisibility_ANY);
     std::set<VariationID> variation_ids;
     std::set<VariationID> trigger_ids;
     ASSERT_TRUE(ExtractVariationIds(variations, &variation_ids, &trigger_ids));
@@ -204,7 +221,8 @@ TEST_F(VariationsIdsProviderTest, OnFieldTrialGroupFinalized) {
 
   // Now, get signed-in ids.
   {
-    std::string variations = provider.GetClientDataHeader(true);
+    std::string variations = provider.GetClientDataHeader(
+        /*is_signed_in=*/true, Study_GoogleWebVisibility_ANY);
     std::set<VariationID> variation_ids;
     std::set<VariationID> trigger_ids;
     ASSERT_TRUE(ExtractVariationIds(variations, &variation_ids, &trigger_ids));

content/browser/field_trial_synchronizer.cc

@@ -117,6 +117,8 @@ void FieldTrialSynchronizer::UpdateRendererVariationsHeader(
       renderer_variations_configuration;
   channel->GetRemoteAssociatedInterface(&renderer_variations_configuration);
 
+  // TODO(crbug/1094303): Consider both variations::Study_GoogleWebVisibility
+  // values.
   renderer_variations_configuration->SetVariationsHeader(
       client->GetVariationsHeader());
 }

weblayer/BUILD.gn

@@ -429,6 +429,7 @@ source_set("weblayer_lib_base") {
     "//components/user_prefs",
     "//components/variations",
     "//components/variations/net",
+    "//components/variations/proto",
     "//components/variations/service",
     "//components/version_info",
     "//components/viz/common",

weblayer/browser/browser_context_impl.cc

@@ -25,6 +25,7 @@
 #include "components/translate/core/browser/translate_pref_names.h"
 #include "components/translate/core/browser/translate_prefs.h"
 #include "components/user_prefs/user_prefs.h"
+#include "components/variations/proto/study.pb.h"
 #include "components/variations/variations_client.h"
 #include "components/variations/variations_ids_provider.h"
 #include "content/public/browser/device_service.h"
@@ -295,9 +296,13 @@ class BrowserContextImpl::WebLayerVariationsClient
     return browser_context_->IsOffTheRecord();
   }
 
+  // TODO(crbug/1094303): Update the signature to accept a
+  // variations::Study_GoogleWebVisibility and pass the given value to
+  // GetClientDataHeader().
   std::string GetVariationsHeader() const override {
     return variations::VariationsIdsProvider::GetInstance()
-        ->GetClientDataHeader(IsSignedIn());
+        ->GetClientDataHeader(IsSignedIn(),
+                              variations::Study_GoogleWebVisibility_ANY);
   }
 
  private: