Remove implementation of Panels on OSes other than ChromeOS.

chrome/browser/task_manager/providers/web_contents/panel_tag.cc

Index: chrome/browser/task_manager/providers/web_contents/panel_tag.cc
diff --git a/chrome/browser/task_manager/providers/web_contents/panel_tag.cc b/chrome/browser/task_manager/providers/web_contents/panel_tag.cc
deleted file mode 100644
index d65bec87e69094c8af85b91f20f9dfe4cfb6304e..0000000000000000000000000000000000000000
--- a/chrome/browser/task_manager/providers/web_contents/panel_tag.cc
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2015 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/task_manager/providers/web_contents/panel_tag.h"
-
-#include "chrome/browser/ui/panels/panel.h"
-
-namespace task_manager {
-
-PanelTask* PanelTag::CreateTask() const {
-  return new PanelTask(panel_, web_contents());
-}
-
-PanelTag::PanelTag(content::WebContents* web_contents, Panel* panel)
-    : WebContentsTag(web_contents),
-      panel_(panel) {
-}
-
-PanelTag::~PanelTag() {
-}
-
-}  // namespace task_manager