[privacy_budget] Enable study for waterfall testing.

R=rkaplow@chromium.org

Bug: 973801
Change-Id: Ib9a9bf27a91df5635751ff08f97f6133350ded77
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2313896
Commit-Queue: Asanka Herath <asanka@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Auto-Submit: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792715}

chrome/browser/privacy_budget/BUILD.gn

@@ -69,6 +69,7 @@ source_set("browser_tests") {
     "//chrome/test:test_support",
     "//components/ukm:test_support",
     "//components/ukm:ukm_test_helper",
+    "//components/variations/service:buildflags",
     "//third_party/blink/public/common/privacy_budget",
   ]
 

chrome/browser/privacy_budget/privacy_budget_browsertest.cc

@@ -9,6 +9,7 @@
 #include "chrome/common/privacy_budget/scoped_privacy_budget_config.h"
 #include "chrome/test/base/chrome_test_utils.h"
 #include "components/ukm/test_ukm_recorder.h"
+#include "components/variations/service/buildflags.h"
 #include "content/public/test/browser_test.h"
 #include "content/public/test/browser_test_utils.h"
 #include "services/metrics/public/cpp/ukm_builders.h"
@@ -108,3 +109,23 @@ IN_PROC_BROWSER_TEST_F(PrivacyBudgetBrowserTest, SamplingScreenAPIs) {
                              .ToUkmMetricHash()));
   }
 }
+
+#if BUILDFLAG(FIELDTRIAL_TESTING_ENABLED)
+
+namespace {
+class PrivacyBudgetDefaultConfigBrowserTest : public PlatformBrowserTest {};
+}  // namespace
+
+// //testing/variations/fieldtrial_testing_config.json defines a set of
+// parameters that should effectively enable the identifiability study for
+// browser tests. This test verifies that those settings work.
+IN_PROC_BROWSER_TEST_F(PrivacyBudgetDefaultConfigBrowserTest, Variations) {
+  EXPECT_TRUE(base::FeatureList::IsEnabled(features::kIdentifiabilityStudy));
+
+  auto* settings = blink::IdentifiabilityStudySettings::Get();
+  EXPECT_TRUE(settings->IsActive());
+  EXPECT_TRUE(settings->IsTypeAllowed(
+      blink::IdentifiableSurface::Type::kCanvasReadback));
+}
+
+#endif

testing/variations/fieldtrial_testing_config.json

@@ -3568,6 +3568,31 @@
             ]
         }
     ],
+    "Identifiability": [
+        {
+            "platforms": [
+                "windows",
+                "mac",
+                "chromeos",
+                "linux",
+                "android",
+                "android_webview"
+            ],
+            "experiments": [
+                {
+                    "name": "G1",
+                    "params": {
+                        "Gen": "1",
+                        "Max": "10",
+                        "Rho": "1000"
+                    },
+                    "enable_features": [
+                        "IdentifiabilityStudy"
+                    ]
+                }
+            ]
+        }
+    ],
     "IdentityDiscIPH": [
         {
             "platforms": [