Add ime native deocoder in flags

Add the IME decoder flag in the chrome://flags, so that QA/Dev can turn
on/off the feature to verify native deocers.

Bug: 837156
Change-Id: I6ace99acf2127958ec4f0868962c721c035fd06d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1866370
Commit-Queue: Leo Zhang <googleo@chromium.org>
Reviewed-by: David Vallet <dvallet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708155}

chrome/browser/about_flags.cc

@@ -2486,6 +2486,9 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kImeInputLogicFstName,
      flag_descriptions::kImeInputLogicFstDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(chromeos::features::kImeInputLogicFst)},
+    {"enable-cros-ime-native-decoder", flag_descriptions::kImeNativeDecoderName,
+     flag_descriptions::kImeNativeDecoderDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(chromeos::features::kImeDecoderWithSandbox)},
     {"enable-experimental-accessibility-switch-access",
      flag_descriptions::kExperimentalAccessibilitySwitchAccessName,
      flag_descriptions::kExperimentalAccessibilitySwitchAccessDescription,

chrome/browser/flag-metadata.json

@@ -1131,7 +1131,12 @@
   {
     "name": "enable-cros-ime-input-logic-fst",
     "owners": [ "essential-inputs-team@google.com" ],
-    "expiry_milestone": 77
+    "expiry_milestone": 80
+  },
+  {
+    "name": "enable-cros-ime-native-decoder",
+    "owners": [ "essential-inputs-team@google.com" ],
+    "expiry_milestone": 85
   },
   {
     "name": "enable-cssom-view-scroll-coordinates",

chrome/browser/flag_descriptions.cc

@@ -3554,6 +3554,10 @@ const char kImeInputLogicFstName[] = "Enable FST Input Logic on IME";
 const char kImeInputLogicFstDescription[] =
     "Enable FST Input Logic to replace the IME legacy input logic on NaCl";
 
+const char kImeNativeDecoderName[] = "Enable native decoders in IME Service";
+const char kImeNativeDecoderDescription[] =
+    "Enable native decoders in IME service to deprecate NaCl decoders";
+
 const char kListAllDisplayModesName[] = "List all display modes";
 const char kListAllDisplayModesDescription[] =
     "Enables listing all external displays' modes in the display settings.";

chrome/browser/flag_descriptions.h

@@ -2112,6 +2112,9 @@ extern const char kHideArcMediaNotificationsDescription[];
 extern const char kImeInputLogicFstName[];
 extern const char kImeInputLogicFstDescription[];
 
+extern const char kImeNativeDecoderName[];
+extern const char kImeNativeDecoderDescription[];
+
 extern const char kListAllDisplayModesName[];
 extern const char kListAllDisplayModesDescription[];
 

tools/metrics/histograms/enums.xml

@@ -35996,8 +35996,10 @@ Called by update_gpu_driver_bug_workaround_entries.py.-->
   <int value="-1197035323" label="ZeroSuggestRedirectToChrome:disabled"/>
   <int value="-1195194959" label="XGEOVisibleNetworks:disabled"/>
   <int value="-1190174011" label="enable-hdr"/>
+  <int value="-1185477291" label="ImeDecoderWithSandbox:enabled"/>
   <int value="-1184904651" label="enable-npapi"/>
   <int value="-1184480269" label="LsdPermissionPrompt:enabled"/>
+  <int value="-1183321008" label="ImeDecoderWithSandbox:disabled"/>
   <int value="-1183009666" label="OfflinePagesLimitlessPrefetching:disabled"/>
   <int value="-1177802205" label="enable-hosted-app-quit-notification"/>
   <int value="-1176748003"