Add flags entry to enable Chrome OS component updates fature.

This adds an entry to about:flags so that users, and internal testers,
can opt into Chrome OS component updates before we roll them out to all
users.

This was originally landed in https://codereview.chromium.org/2544133002,
but reverted in https://codereview.chromium.org/2567773002
because one of the other flags did not work properly.

BUG=670421

Review-Url: https://codereview.chromium.org/2565043002
Cr-Commit-Position: refs/heads/master@{#437774}

chrome/app/generated_resources.grd

@@ -15692,6 +15692,13 @@ read aloud to screenreader users to announce that a completion is available.">
     <message name="IDS_FLAGS_MEDIA_REMOTING_ENCRYPTED_DESCRIPTION" desc="Desciption for the flag to enable Media Remoting of encrypted content" translateable="false">
       When Media Remoting is enabled, this flag must be enabled to allow the remoting of encrypted content. When disabled, only non-encrypted content can be remoted.
     </message>
+    <!-- Chrome OS component updates chrome://flags strings -->
+    <message name="IDS_FLAGS_CROS_COMP_UPDATES_NAME" desc="Name for the flag to enable Chrome OS component flash updates" translateable="false">
+      Chrome OS Flash Component Updates
+    </message>
+    <message name="IDS_FLAGS_CROS_COMP_UPDATES_DESCRIPTION" desc="Description for the flag to enable Chrome OS component flash updates" translateable="false">
+      Enable Flash component updates for Chrome OS.
+    </message>
   </messages>
  </release>
 </grit>

chrome/browser/about_flags.cc

@@ -2126,6 +2126,11 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_WITH_VARIATIONS_VALUE_TYPE(prerender::kNoStatePrefetchFeature,
                                         kNoStatePrefetchFeatureVariations,
                                         "NoStatePrefetchValidation")},
+#if defined(OS_CHROMEOS)
+    {"cros-comp-updates", IDS_FLAGS_CROS_COMP_UPDATES_NAME,
+     IDS_FLAGS_CROS_COMP_UPDATES_DESCRIPTION, kOsCrOS,
+     FEATURE_VALUE_TYPE(features::kCrosCompUpdates)},
+#endif
 
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in

chrome/browser/component_updater/pepper_flash_component_installer.cc

@@ -45,9 +45,9 @@
 #include "ppapi/shared_impl/ppapi_permissions.h"
 
 #if defined(OS_CHROMEOS)
-#include "base/feature_list.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "chrome/browser/ui/ash/system_tray_delegate_chromeos.h"
+#include "chrome/common/chrome_features.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/image_loader_client.h"
@@ -114,10 +114,7 @@ void ImageLoaderRegistration(const std::string& version,
 
 // Determine whether or not to skip registering flash component updates.
 bool SkipFlashRegistration(ComponentUpdateService* cus) {
-   const base::Feature kCrosCompUpdates {
-     "CrosCompUpdates", base::FEATURE_DISABLED_BY_DEFAULT
-   };
-   if (!base::FeatureList::IsEnabled(kCrosCompUpdates))
+   if (!base::FeatureList::IsEnabled(features::kCrosCompUpdates))
      return true;
 
    // If the version of Chrome is pinned on the device (probably via enterprise

chrome/common/chrome_features.cc

@@ -230,6 +230,10 @@ const base::Feature kQuickUnlockPin{"QuickUnlockPin",
 // Enables or disables emoji, handwriting and voice input on opt-in IME menu.
 const base::Feature kEHVInputOnImeMenu{"EmojiHandwritingVoiceInput",
                                        base::FEATURE_DISABLED_BY_DEFAULT};
+
+// Enables or disables flash component updates on Chrome OS.
+const base::Feature kCrosCompUpdates{"CrosCompUpdates",
+                                     base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace features

chrome/common/chrome_features.h

@@ -133,6 +133,8 @@ extern const base::Feature kOptInImeMenu;
 extern const base::Feature kQuickUnlockPin;
 
 extern const base::Feature kEHVInputOnImeMenu;
+
+extern const base::Feature kCrosCompUpdates;
 #endif  // defined(OS_CHROMEOS)
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in

tools/metrics/histograms/histograms.xml

@@ -92883,6 +92883,7 @@ value.
   <int value="-1473668019" label="token-binding:disabled"/>
   <int value="-1473136627" label="enable-web-payments"/>
   <int value="-1467332609" label="tab-management-experiment-type-anise"/>
+  <int value="-1466990325" label="CrosCompUpdates:enabled"/>
   <int value="-1460462432" label="disable-media-source"/>
   <int value="-1456004000" label="VrShell:disabled"/>
   <int value="-1443796945" label="OfflinePagesSharing:disabled"/>
@@ -93060,6 +93061,7 @@ value.
   <int value="-641719457" label="disable-compositor-touch-hit-testing"/>
   <int value="-631740127" label="inert-visual-viewport"/>
   <int value="-622685174" label="enable-pdf-material-ui"/>
+  <int value="-620030047" label="CrosCompUpdates:disabled"/>
   <int value="-617452890" label="media-router"/>
   <int value="-610411643" label="enable-printer-app-search"/>
   <int value="-606898702" label="MaterialDesignSettings:disabled"/>