[butter/self-share] Add chrome://flags entry for butterified STTS

Add an entry to chrome://flags to make testing easier.

Bug: 956722
Change-Id: If91fdcbecc4293e844585babfdf51b3e2022dc3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2613053
Commit-Queue: Victor Vianna <victorvianna@google.com>
Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Auto-Submit: Victor Vianna <victorvianna@google.com>
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841059}

chrome/browser/about_flags.cc

@@ -6952,6 +6952,12 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kActionableContentSettingsDescription, kOsAndroid,
      FEATURE_VALUE_TYPE(browser_ui::kActionableContentSettings)},
 #endif
+
+    {"send-tab-to-self-when-signed-in",
+     flag_descriptions::kSendTabToSelfWhenSignedInName,
+     flag_descriptions::kSendTabToSelfWhenSignedInDescription, kOsAll,
+     FEATURE_VALUE_TYPE(send_tab_to_self::kSendTabToSelfWhenSignedIn)},
+
     // NOTE: Adding a new flag requires adding a corresponding entry to enum
     // "LoginCustomFlags" in tools/metrics/histograms/enums.xml. See "Flag
     // Histograms" in tools/metrics/histograms/README.md (run the

chrome/browser/flag-metadata.json

@@ -4368,6 +4368,11 @@
     "owners": [ "joelriley" ],
     "expiry_milestone": 89
   },
+  {
+    "name": "send-tab-to-self-when-signed-in",
+    "owners": ["victorvianna@google.com", "mastiz@chromium.org"],
+    "expiry_milestone": 92
+  },
   {
     "name": "send-uma-cellular",
     "owners": [ "thegreenfrog", "bling-flags@google.com" ],

chrome/browser/flag_descriptions.cc

@@ -2047,6 +2047,11 @@ const char kSecurePaymentConfirmationDebugDescription[] =
     "secure payment confirmation in PaymentRequest API must use user verifying "
     "platform authenticators.";
 
+const char kSendTabToSelfWhenSignedInName[] = "Send tab to self when signed-in";
+const char kSendTabToSelfWhenSignedInDescription[] =
+    "Makes the tab sharing feature also available for users who have \"only\" "
+    "signed-in to their Google Account (as opposed to having enabled Sync).";
+
 const char kSidePanelName[] = "Side panel";
 const char kSidePanelDescription[] = "Host some content in a side panel.";
 

chrome/browser/flag_descriptions.h

@@ -1191,6 +1191,9 @@ extern const char kScrollUnificationDescription[];
 extern const char kSecurePaymentConfirmationDebugName[];
 extern const char kSecurePaymentConfirmationDebugDescription[];
 
+extern const char kSendTabToSelfWhenSignedInName[];
+extern const char kSendTabToSelfWhenSignedInDescription[];
+
 extern const char kSidePanelName[];
 extern const char kSidePanelDescription[];