[ios] Create Feature Flag for Translate Messages UI

Bug: 1014959
Change-Id: I72f36884a3bc36e7d39a93314ec3c4e770ddd10a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869371
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707557}

ios/chrome/browser/flags/about_flags.mm

@@ -564,6 +564,10 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kSaveCardInfobarMessagesUIName,
      flag_descriptions::kSaveCardInfobarMessagesUIDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(kSaveCardInfobarMessagesUI)},
+    {"messages-translate-infobar",
+     flag_descriptions::kTranslateInfobarMessagesUIName,
+     flag_descriptions::kTranslateInfobarMessagesUIDescription,
+     flags_ui::kOsIos, FEATURE_VALUE_TYPE(kTranslateInfobarMessagesUI)},
 };
 
 // Add all switches from experimental flags to |command_line|.

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -365,6 +365,11 @@ const char kToolbarNewTabButtonName[] =
 const char kToolbarNewTabButtonDescription[] =
     "When enabled, the bottom toolbar middle button opens a new tab";
 
+const char kTranslateInfobarMessagesUIName[] =
+    "Enable Translate Infobar Messages UI";
+const char kTranslateInfobarMessagesUIDescription[] =
+    "When enabled, the Translate Infobar uses the new Messages UI.";
+
 const char kUseDdljsonApiName[] = "Use new ddljson API for Doodles";
 const char kUseDdljsonApiDescription[] =
     "Enables the new ddljson API to fetch Doodles for the NTP.";

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -320,6 +320,11 @@ extern const char kToolbarContainerDescription[];
 extern const char kToolbarNewTabButtonName[];
 extern const char kToolbarNewTabButtonDescription[];
 
+// Title and description for the flag to enable the Messages UI for Translate
+// Infobars.
+extern const char kTranslateInfobarMessagesUIName[];
+extern const char kTranslateInfobarMessagesUIDescription[];
+
 // Title and description for the flag to enable the ddljson Doodle API.
 extern const char kUseDdljsonApiName[];
 extern const char kUseDdljsonApiDescription[];

ios/chrome/browser/ui/infobars/infobar_feature.h

@@ -24,6 +24,12 @@ extern const base::Feature kConfirmInfobarMessagesUI;
 // Use IsSaveCardInfobarMessagesUIEnabled() instead of this constant directly.
 extern const base::Feature kSaveCardInfobarMessagesUI;
 
+// Feature to choose whether Translate Infobar uses the new Messages UI or the
+// legacy one. In order for it to work, kInfobarUIReboot needs to also be
+// enabled.
+// Use IsTranslateInfobarMessagesUIEnabled() instead of this constant directly.
+extern const base::Feature kTranslateInfobarMessagesUI;
+
 // Whether the Messages Infobar UI is enabled.
 bool IsInfobarUIRebootEnabled();
 
@@ -33,4 +39,7 @@ bool IsConfirmInfobarMessagesUIEnabled();
 // Whether the SaveCard Infobar Messages UI is enabled.
 bool IsSaveCardInfobarMessagesUIEnabled();
 
+// Whether the Translate Infobar Messages UI is enabled.
+bool IsTranslateInfobarMessagesUIEnabled();
+
 #endif  // IOS_CHROME_BROWSER_UI_INFOBARS_INFOBAR_FEATURE_H_

ios/chrome/browser/ui/infobars/infobar_feature.mm

@@ -24,6 +24,13 @@ const base::Feature kConfirmInfobarMessagesUI{"ConfirmInfobarMessagesUI",
 const base::Feature kSaveCardInfobarMessagesUI{
     "SaveCardInfobarMessagesUI", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Feature enabled by default since it will always be guarded with
+// |kInfobarUIReboot|, meaning that if necessary, |kInfobarUIReboot| can be used
+// as a kill switch.
+// TODO(crbug.com/1014959): Enabled flag once feature is ready.
+const base::Feature kTranslateInfobarMessagesUI{
+    "TranslateInfobarMessagesUI", base::FEATURE_DISABLED_BY_DEFAULT};
+
 bool IsInfobarUIRebootEnabled() {
   return base::FeatureList::IsEnabled(kInfobarUIReboot);
 }
@@ -37,3 +44,8 @@ bool IsSaveCardInfobarMessagesUIEnabled() {
   return base::FeatureList::IsEnabled(kSaveCardInfobarMessagesUI) &&
          IsInfobarUIRebootEnabled();
 }
+
+bool IsTranslateInfobarMessagesUIEnabled() {
+  return base::FeatureList::IsEnabled(kTranslateInfobarMessagesUI) &&
+         IsInfobarUIRebootEnabled();
+}