[Extensions Click-to-Script] Enable by default

Flip the RuntimeHostPermissions feature to be enabled by default on
ToT. Remove the entry in the testing config.

Bug: 869996
Change-Id: Ic76c4a018c6bc0140069bd2730ff5591cd293bda
Reviewed-on: https://chromium-review.googlesource.com/c/1294010Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605097}

extensions/common/extension_features.cc

@@ -17,6 +17,6 @@ const base::Feature kNewExtensionUpdaterService{
 // Forces extensions with <all_hosts> to use activeTab-style runtime host
 // permissions.
 const base::Feature kRuntimeHostPermissions{"RuntimeHostPermissions",
-                                            base::FEATURE_DISABLED_BY_DEFAULT};
+                                            base::FEATURE_ENABLED_BY_DEFAULT};
 
 }  // namespace extensions_features

testing/variations/fieldtrial_testing_config.json

@@ -3965,24 +3965,6 @@
             ]
         }
     ],
-    "RuntimeHostPermissions": [
-        {
-            "platforms": [
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "RuntimeHostPermissions"
-                    ]
-                }
-            ]
-        }
-    ],
     "SRTPromptFieldTrial": [
         {
             "platforms": [