Add flags for CrOS Component using Feature API

This CL adds flags to enable/disable Chrome OS Component
(go/cros_component).

BUG=chromium:690521
TEST= Chrome OS Compnent shows up in Chrome://flags

Review-Url: https://codereview.chromium.org/2856913005
Cr-Commit-Position: refs/heads/master@{#469266}

chrome/browser/about_flags.cc

@@ -2310,6 +2310,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"disable-native-cups", flag_descriptions::kDisableNativeCupsName,
      flag_descriptions::kDisableNativeCupsDescription, kOsCrOS,
      SINGLE_VALUE_TYPE(switches::kDisableNativeCups)},
+    {"enable-cros-component", flag_descriptions::kCrOSComponentName,
+     flag_descriptions::kCrOSComponentDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(features::kCrOSComponent)},
     {"enable-encryption-migration",
      flag_descriptions::kEnableEncryptionMigrationName,
      flag_descriptions::kEnableEncryptionMigrationDescription, kOsCrOS,

chrome/browser/flag_descriptions.cc

@@ -2332,6 +2332,12 @@ const char kEnableZipArchiverOnFileManagerName[] =
 const char kEnableZipArchiverOnFileManagerDescription[] =
     "Enable the ability to archive and unpack files on Drive in the Files app";
 
+const char kCrOSComponentName[] = "Chrome OS Component";
+
+const char kCrOSComponentDescription[] =
+    "Enable the use of Chrome OS Component to download Chrome OS features "
+    "on-demand as components.";
+
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(OS_ANDROID)

chrome/browser/flag_descriptions.h

@@ -1066,6 +1066,12 @@ extern const char kTetherName[];
 // Description for the flag for enabling Instant Tethering.
 extern const char kTetherDescription[];
 
+// Name for the flag for CrOS Component.
+extern const char kCrOSComponentName[];
+
+// Description for the flag for CrOS Component.
+extern const char kCrOSComponentDescription[];
+
 #endif  // defined(OS_CHROMEOS)
 
 // Name of the flag for accelerated video decode where available.

chrome/common/chrome_features.cc

@@ -340,6 +340,10 @@ const base::Feature kEHVInputOnImeMenu{"EmojiHandwritingVoiceInput",
 // Enables or disables flash component updates on Chrome OS.
 const base::Feature kCrosCompUpdates{"CrosCompUpdates",
                                      base::FEATURE_ENABLED_BY_DEFAULT};
+
+// Enables or disables Chrome OS Component updates on Chrome OS.
+const base::Feature kCrOSComponent{"CrOSComponent",
+                                   base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS)
 
 bool PrefServiceEnabled() {

chrome/common/chrome_features.h

@@ -187,6 +187,8 @@ extern const base::Feature kQuickUnlockFingerprint;
 extern const base::Feature kEHVInputOnImeMenu;
 
 extern const base::Feature kCrosCompUpdates;
+
+extern const base::Feature kCrOSComponent;
 #endif  // defined(OS_CHROMEOS)
 
 bool PrefServiceEnabled();

tools/metrics/histograms/enums.xml

@@ -20609,6 +20609,7 @@ from previous Chrome versions.
   <int value="-2047832738" label="enable-system-timezone-automatic-detection"/>
   <int value="-2047822258" label="enable-avfoundation"/>
   <int value="-2043128632" label="enable-tab-switcher-in-document-mode"/>
+  <int value="-2040471724" label="CrOSComponent:disabled"/>
   <int value="-2040115518" label="load-media-router-component-extension"/>
   <int value="-2029912304" label="StaleWhileRevalidate2:enabled"/>
   <int value="-2025367104" label="enable-material-design-ntp"/>
@@ -21253,6 +21254,7 @@ from previous Chrome versions.
   <int value="458410433" label="disable-views-rect-based-targeting"/>
   <int value="460136092" label="MidiManagerAndroid:disabled"/>
   <int value="460475728" label="wake-on-wifi-packet"/>
+  <int value="464226051" label="CrOSComponent:enabled"/>
   <int value="466248382" label="disable-push-api-background-mode"/>
   <int value="468959230"
       label="enable-non-validating-reload-on-refresh-content"/>