Adding about flags for federated service

It can be used as a kill switch to disable all federated service
related activities if the user turns if off. Turning it on doesn't
necessarily mean all federated service tasks will run because there are
other flags & attached parameters controlling the per federated client
behaviors.

Bug: b:239623649
Test: unit_tests --gtest_filter=AboutFlagsHistogramTest.CheckHistograms
Test: unit_tests --gtest_filter=AboutFlagsTest.EveryFlagHasMetadata
Change-Id: I7420566d54fd76823190fa95267a184a3943a0a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4569414
Reviewed-by: Andrew Moylan <amoylan@chromium.org>
Quick-Run: Xinglong Luan <alanlxl@chromium.org>
Commit-Queue: Xinglong Luan <alanlxl@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1150356}

chrome/browser/about_flags.cc

@@ -5421,6 +5421,9 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kSystemProxyForSystemServicesName,
      flag_descriptions::kSystemProxyForSystemServicesDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(ash::features::kSystemProxyForSystemServices)},
+    {"enable-federated-service", flag_descriptions::kFederatedServiceName,
+     flag_descriptions::kFederatedServiceDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(ash::features::kFederatedService)},
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)
 #if BUILDFLAG(IS_CHROMEOS)
     {"enable-cros-touch-text-editing-redesign",

chrome/browser/flag-metadata.json

@@ -2454,6 +2454,11 @@
     "owners": ["wmahon", "chromeos-tango@google.com"],
     "expiry_milestone": 115
   },
+  {
+    "name": "enable-federated-service",
+    "owners": [ "alanlxl", "amoylan"],
+    "expiry_milestone": 120
+  },
   {
     "name": "enable-feed-ablation",
     "owners": [ "adamta", "sczs" ],

chrome/browser/flag_descriptions.cc

@@ -5865,6 +5865,11 @@ const char kExposeOutOfProcessVideoDecodingToLacrosDescription[] =
     "Accept media.stable.mojom.StableVideoDecoderFactory connection requests "
     "from LaCrOS and host said factories in utility processes.";
 
+const char kFederatedServiceName[] =
+    "Enable Federated Service on ChromeOS login";
+const char kFederatedServiceDescription[] =
+    "If disalbed, all federated service activities are stopped.";
+
 const char kFileTransferEnterpriseConnectorName[] =
     "Enable Files Transfer Enterprise Connector.";
 const char kFileTransferEnterpriseConnectorDescription[] =

chrome/browser/flag_descriptions.h

@@ -3358,6 +3358,9 @@ extern const char kExperimentalAccessibilitySwitchAccessTextDescription[];
 extern const char kExposeOutOfProcessVideoDecodingToLacrosName[];
 extern const char kExposeOutOfProcessVideoDecodingToLacrosDescription[];
 
+extern const char kFederatedServiceName[];
+extern const char kFederatedServiceDescription[];
+
 extern const char kFileTransferEnterpriseConnectorName[];
 extern const char kFileTransferEnterpriseConnectorDescription[];
 

tools/metrics/histograms/enums.xml

@@ -62028,6 +62028,7 @@ from previous Chrome versions.
   <int value="-438379844" label="SwapSideVolumeButtonsForOrientation:enabled"/>
   <int value="-438348502" label="LogUrlScoringSignals:disabled"/>
   <int value="-437292646" label="DeferBeginMainFrameDuringLoading:enabled"/>
+  <int value="-436799973" label="FederatedService:enabled"/>
   <int value="-436470115" label="TouchpadAndWheelScrollLatching:enabled"/>
   <int value="-435914745" label="ClipboardContentSetting:disabled"/>
   <int value="-435636565" label="EnableLensPing:disabled"/>
@@ -65316,6 +65317,7 @@ from previous Chrome versions.
   <int value="1313608203"
       label="TabbedAppOverflowMenuThreeButtonActionbar:enabled"/>
   <int value="1313850691" label="Metal:disabled"/>
+  <int value="1314067176" label="FederatedService:disabled"/>
   <int value="1314681756" label="NoStatePrefetch:disabled"/>
   <int value="1314797690"
       label="CCTRealTimeEngagementSignalsAlternativeImpl:disabled"/>