[Document Policy] Supports runtime flag controlled default value

Example config in "document_policy_features.cc":
    {
      name: "DefaultValueFeatureForTest",
      document_policy_name: "_reserved",
      value_type: "Bool",
      default_value: "true",
      depends_on: [],
      default_value_behind_flag: [
        ["PaintHolding", "false"],
        ["ScriptStreaming", "true"],
      ]
    },

Generated output:
const DocumentPolicyFeatureInfoMap& GetDocumentPolicyFeatureInfoMap() {
  static const base::NoDestructor<DocumentPolicyFeatureInfoMap> feature_info_map([] {
    DocumentPolicyFeatureInfoMap map({        {
          mojom::DocumentPolicyFeature::kDefaultValueFeatureForTest,
          {
            "",
            PolicyValue::CreateBool(true)
          }
        }, ...});

        if (base::FeatureList::IsEnabled(features::kPaintHolding)) {
          map.insert_or_assign(
            mojom::DocumentPolicyFeature::kDefaultValueFeatureForTest,
            DocumentPolicyFeatureInfo {
              "",
              PolicyValue::CreateBool(false)
            }
          );
        } else if (base::FeatureList::IsEnabled(features::kScriptStreaming)) {
          map.insert_or_assign(
            mojom::DocumentPolicyFeature::kDefaultValueFeatureForTest,
            DocumentPolicyFeatureInfo {
              "",
              PolicyValue::CreateBool(true)
            }
          );
        }
    return map;
  }());
  return *feature_info_map;
}

Bug: 1166698
Change-Id: Ib0bf5905ddcccface2673486181616662c6e2b7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2534612
Commit-Queue: Charlie Hu <chenleihu@google.com>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Ian Clelland <iclelland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843716}

content/browser/renderer_host/render_frame_host_impl_browsertest.cc

@@ -6767,6 +6767,70 @@ IN_PROC_BROWSER_TEST_F(RenderFrameHostImplBrowserTest,
   EXPECT_EQ("POST", root_frame_host()->last_http_method());
 }
 
+struct DocumentPolicyDefaultValueBrowserTestCase {
+  std::initializer_list<base::Feature> enabled_features;
+  std::initializer_list<base::Feature> disabled_features;
+  bool expected_feature_state;
+};
+
+// The test on Document Policy default value control must be browsertest
+// as the initialization of default value in
+// |blink::GetDocumentPolicyFeatureInfoMap| only happens once per browser
+// instance.
+class DocumentPolicyDefaultValueBrowserTest
+    : public RenderFrameHostImplBrowserTest,
+      public ::testing::WithParamInterface<
+          DocumentPolicyDefaultValueBrowserTestCase> {
+ public:
+  static const DocumentPolicyDefaultValueBrowserTestCase kCases[];
+
+  DocumentPolicyDefaultValueBrowserTest() {
+    const auto& test_case = GetParam();
+    feature_list_.InitWithFeatures(test_case.enabled_features,
+                                   test_case.disabled_features);
+  }
+
+ private:
+  base::test::ScopedFeatureList feature_list_;
+};
+
+// Following flag control logic is defined in
+// blink/renderer/core/feature_policy/document_policy_features.json5.
+const DocumentPolicyDefaultValueBrowserTestCase
+    DocumentPolicyDefaultValueBrowserTest::kCases[] = {
+        {{},
+         {blink::features::kDocumentPolicyRuntimeFlag1ForTest,
+          blink::features::kDocumentPolicyRuntimeFlag2ForTest},
+         true},
+        {{blink::features::kDocumentPolicyRuntimeFlag1ForTest},
+         {blink::features::kDocumentPolicyRuntimeFlag2ForTest},
+         false},
+        {{blink::features::kDocumentPolicyRuntimeFlag2ForTest},
+         {blink::features::kDocumentPolicyRuntimeFlag1ForTest},
+         true},
+        {{blink::features::kDocumentPolicyRuntimeFlag2ForTest,
+          blink::features::kDocumentPolicyRuntimeFlag1ForTest},
+         {},
+         false},
+};
+
+INSTANTIATE_TEST_SUITE_P(
+    All,
+    DocumentPolicyDefaultValueBrowserTest,
+    testing::ValuesIn(DocumentPolicyDefaultValueBrowserTest::kCases));
+
+IN_PROC_BROWSER_TEST_P(DocumentPolicyDefaultValueBrowserTest,
+                       DocumentPolicyDefaultValueBehindFlag) {
+  const auto& test_case = GetParam();
+  std::unique_ptr<blink::DocumentPolicy> document_policy =
+      blink::DocumentPolicy::CreateWithHeaderPolicy({});
+
+  EXPECT_EQ(
+      document_policy->IsFeatureEnabled(
+          blink::mojom::DocumentPolicyFeature::kDefaultValueFeatureForTest),
+      test_case.expected_feature_state);
+}
+
 // Check Chrome won't attempt automatically loading the /favicon.ico if it would
 // be blocked by CSP.
 IN_PROC_BROWSER_TEST_F(RenderFrameHostImplBrowserTest,

third_party/blink/common/features.cc

@@ -866,5 +866,11 @@ const base::Feature kInterestCohortAPIOriginTrial{
 const base::Feature kInterestCohortFeaturePolicy{
     "InterestCohortFeaturePolicy", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Flags only used for testing purposes. No effect when enabled.
+const base::Feature kDocumentPolicyRuntimeFlag1ForTest{
+    "kDocumentPolicyRuntimeFlag1ForTest", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kDocumentPolicyRuntimeFlag2ForTest{
+    "kDocumentPolicyRuntimeFlag2ForTest", base::FEATURE_DISABLED_BY_DEFAULT};
+
 }  // namespace features
 }  // namespace blink

third_party/blink/public/common/features.h

@@ -356,6 +356,13 @@ BLINK_COMMON_EXPORT extern const base::Feature kInterestCohortAPIOriginTrial;
 
 BLINK_COMMON_EXPORT extern const base::Feature kInterestCohortFeaturePolicy;
 
+// Flags used to test DocumentPolicy's default value being controlled by
+// different runtime flag states.
+BLINK_COMMON_EXPORT extern const base::Feature
+    kDocumentPolicyRuntimeFlag1ForTest;
+BLINK_COMMON_EXPORT extern const base::Feature
+    kDocumentPolicyRuntimeFlag2ForTest;
+
 }  // namespace features
 }  // namespace blink
 

third_party/blink/public/mojom/feature_policy/document_policy_feature.mojom

@@ -36,6 +36,9 @@ enum DocumentPolicyFeature {
   kJSProfiling = 11,
   // Controls use of synchronous XMLHTTPRequest API.
   kSyncXHR = 12,
+  // Feature for testing 'default_value_behind_flag' field in
+  // document_policy_features.json5.
+  kDefaultValueFeatureForTest = 13,
   // Don't change assigned numbers of any item, and don't reuse removed slots.
   // Add new features at the end of the enum.
   // Also, run update_document_policy_enum.py in

third_party/blink/renderer/build/scripts/templates/document_policy_features.cc.tmpl

@@ -4,6 +4,8 @@
 {{ source_files_for_generated_file(template_file, input_files) }}
 
 #include "base/no_destructor.h"
+#include "base/feature_list.h"
+#include "third_party/blink/public/common/features.h"
 #include "third_party/blink/public/common/feature_policy/document_policy_features.h"
 #include "third_party/blink/public/common/feature_policy/policy_value.h"
 #include "third_party/blink/public/mojom/feature_policy/policy_value.mojom.h"
@@ -13,17 +15,38 @@
 namespace blink {
 
 const DocumentPolicyFeatureInfoMap& GetDocumentPolicyFeatureInfoMap() {
-  static const base::NoDestructor<DocumentPolicyFeatureInfoMap> feature_info_map({
-    {%- for feature in features %}
-      {
-        mojom::DocumentPolicyFeature::k{{feature.name}},
+  static const base::NoDestructor<DocumentPolicyFeatureInfoMap> feature_info_map([] {
+    DocumentPolicyFeatureInfoMap map({
+      {%- for feature in features %}
         {
-          "{{feature.document_policy_name}}",
-          {{parse_default_value(feature.default_value, feature.value_type)}}
+          mojom::DocumentPolicyFeature::k{{feature.name}},
+          {
+            "{{feature.document_policy_name}}",
+            {{parse_default_value(feature.default_value, feature.value_type)}}
+          }
+        },
+      {%- endfor %}
+    });
+
+    {%- for feature in features %}
+    {%- if feature.default_value_behind_flag %}
+      {%- for flag, default_value in feature.default_value_behind_flag %}
+        {%- if not loop.first %} else {% endif %}
+        if (base::FeatureList::IsEnabled(features::k{{flag}})) {
+          map.insert_or_assign(
+            mojom::DocumentPolicyFeature::k{{feature.name}},
+            DocumentPolicyFeatureInfo {
+              "{{feature.document_policy_name}}",
+              {{parse_default_value(default_value, feature.value_type)}}
+            }
+          );
         }
-      },
+      {%- endfor %}
+    {%- endif %}
     {%- endfor %}
-  });
+
+    return map;
+  }());
   return *feature_info_map;
 }
 
@@ -38,5 +61,3 @@ const DocumentPolicyNameFeatureMap& GetDocumentPolicyNameFeatureMap() {
 }
 
 } // namespace blink
-
-

third_party/blink/renderer/build/scripts/templates/policy_helper.cc.tmpl

@@ -12,7 +12,6 @@
 #include "third_party/blink/renderer/platform/runtime_enabled_features.h"
 
 namespace blink {
-  
 namespace {
 
 {% for feature in feature_policy_features %}

third_party/blink/renderer/core/feature_policy/document_policy_features.json5

 {
   // All document policy (https://w3c.github.io/webappsec-feature-policy/document-policy.html)
   // features are defined here.
-  // All Features have to be defined in FeaturePolicyFeature enum as well
-  // (defined in third_party/blink/public/mojom/feature_policy/feature_policy.mojom).
+  // All Features have to be defined in DocumentPolicyFeature enum as well
+  // (defined in third_party/blink/public/mojom/feature_policy/document_policy_feature.mojom).
   // The enum value has to have the same name as the feature name here.
 
   parameters: {
@@ -26,9 +26,42 @@
       default: [],
       valid_type: "list",
     },
+    // "default_value_behind_flag" specifies default_value override values
+    // based on different runtime flags set.
+    //
+    // When multiple flags are set, default_value correspond to the first
+    // flag in the list will be used, e.g.
+    //   default_value_behind_flag: [
+    //    ["A", 1.0],
+    //    ["B", 2.0],
+    //   ]
+    // 1.0 will be used as default value when both flag A and B are set.
+    //
+    // Note: the runtime flags here refer to features defined in
+    // "third_party/blink/public/common/features.h", instead of those defined in
+    // "runtime_enabled_features.json5" because the latter is only available
+    // on renderer side, while default_value is needed from browser side as
+    // well.
+    default_value_behind_flag: {
+      default: [],
+      valid_type: "list",
+    }
   },
 
   data: [
+    {
+      name: "DefaultValueFeatureForTest",
+      // Setting document_policy_name to "", so that it will not be recognized
+      // by the parser, as structured header token cannot be empty.
+      document_policy_name: "",
+      value_type: "Bool",
+      default_value: "true",
+      depends_on: [],
+      default_value_behind_flag: [
+        ["DocumentPolicyRuntimeFlag1ForTest", "false"],
+        ["DocumentPolicyRuntimeFlag2ForTest", "true"],
+      ]
+    },
     {
       name: "Default",
       document_policy_name: "*",