Revert "Enable "AsyncDns" feature by default on Android"

This reverts commit 0532f223.

Reason for revert: Full launch needs to be rolled back and retried in a future milestone due to a bug. The experiment cleanup here was premature.

Original change's description:
> Enable "AsyncDns" feature by default on Android
> 
> Also clean up Android-specific experiment code, but leave the
> base::Feature.
> 
> Bug: 768874
> Change-Id: Ic7b81a878e3e81bc1a5c2c2fae242df23c5387ca
> Reviewed-on: https://chromium-review.googlesource.com/868077
> Reviewed-by: Ilya Sherman <isherman@chromium.org>
> Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#529866}

TBR=isherman@chromium.org,mgersh@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 768874, 805020
Change-Id: Ib67c727aef748b4e80714e6128c3bfbdc24d3544
Reviewed-on: https://chromium-review.googlesource.com/881206Reviewed-by: Miriam Gershenson <mgersh@chromium.org>
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531381}

chrome/browser/about_flags.cc

@@ -3518,6 +3518,12 @@ const FeatureEntry kFeatureEntries[] = {
                                     kSpeculativePreconnectFeatureVariations,
                                     "SpeculativePreconnectValidation")},
 
+#if defined(OS_ANDROID)
+    {"enable-async-dns", flag_descriptions::kAsyncDnsName,
+     flag_descriptions::kAsyncDnsDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(features::kAsyncDns)},
+#endif  // defined(OS_ANDROID)
+
     {"enable-overflow-icons-for-media-controls",
      flag_descriptions::kOverflowIconsForMediaControlsName,
      flag_descriptions::kOverflowIconsForMediaControlsDescription, kOsAll,

chrome/browser/flag_descriptions.cc

@@ -1683,6 +1683,9 @@ const char kAndroidViewPasswordsName[] = "Copy and view passwords for Android";
 const char kAndroidViewPasswordsDescription[] =
     "Enables copying and viewing passwords in settings.";
 
+const char kAsyncDnsName[] = "Async DNS resolver";
+const char kAsyncDnsDescription[] = "Enables the built-in DNS resolver.";
+
 const char kAutofillAccessoryViewName[] =
     "Autofill suggestions as keyboard accessory view";
 const char kAutofillAccessoryViewDescription[] =

chrome/browser/flag_descriptions.h

@@ -1035,6 +1035,9 @@ extern const char kAndroidPaymentAppsDescription[];
 extern const char kAndroidViewPasswordsName[];
 extern const char kAndroidViewPasswordsDescription[];
 
+extern const char kAsyncDnsName[];
+extern const char kAsyncDnsDescription[];
+
 extern const char kAutofillAccessoryViewName[];
 extern const char kAutofillAccessoryViewDescription[];
 

chrome/common/chrome_features.cc

@@ -71,7 +71,7 @@ const base::Feature kAssetDownloadSuggestionsFeature{
 // Enables the built-in DNS resolver.
 const base::Feature kAsyncDns {
   "AsyncDns",
-#if defined(OS_CHROMEOS) || defined(OS_MACOSX) || defined(OS_ANDROID)
+#if defined(OS_CHROMEOS) || defined(OS_MACOSX)
       base::FEATURE_ENABLED_BY_DEFAULT
 #else
       base::FEATURE_DISABLED_BY_DEFAULT

testing/variations/fieldtrial_testing_config.json

@@ -372,6 +372,21 @@
             ]
         }
     ],
+    "AsyncDns": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "AsyncDns"
+                    ]
+                }
+            ]
+        }
+    ],
     "AutofillCreditCardBankNameDisplay": [
         {
             "platforms": [