[Extensions] Remove FeatureSwitch::easy_off_store_install

chrome/browser/extensions/extension_install_prompt.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/extension_install_prompt.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/location.h"
@@ skipping 649 matching lines @@
   done_callback_ = done_callback;
   if (icon && !icon->empty())
     SetIcon(icon);
   prompt_ = std::move(prompt);
   custom_permissions_ = std::move(custom_permissions);
   show_dialog_callback_ = show_dialog_callback;
 
   // We special-case themes to not show any confirm UI. Instead they are
   // immediately installed, and then we show an infobar (see OnInstallSuccess)
   // to allow the user to revert if they don't like it.
-  //
-  // We don't do this in the case where off-store extension installs are
-  // disabled because in that case, we don't show the dangerous download UI, so
-  // we need the UI confirmation.
-  if (extension->is_theme()) {
-    if (extension->from_webstore() ||
-        extensions::FeatureSwitch::easy_off_store_install()->IsEnabled()) {
-      base::ResetAndReturn(&done_callback_).Run(Result::ACCEPTED);
-      return;
-    }
+  if (extension->is_theme() && extension->from_webstore()) {
+    base::ResetAndReturn(&done_callback_).Run(Result::ACCEPTED);
+    return;
   }
 
   LoadImageIfNeeded();
 }
 
 void ExtensionInstallPrompt::OnInstallSuccess(const Extension* extension,
                                               SkBitmap* icon) {
   extension_ = extension;
   SetIcon(icon);
 
@@ skipping 132 matching lines @@
 
   if (AutoConfirmPrompt(&done_callback_))
     return;
 
   if (show_dialog_callback_.is_null())
     show_dialog_callback_ = GetDefaultShowDialogCallback();
   base::ResetAndReturn(&show_dialog_callback_)
       .Run(show_params_.get(), base::ResetAndReturn(&done_callback_),
            std::move(prompt_));
 }