linux and chromeos: Turn on -Wunused-const-variable.

chrome/browser/chromeos/file_manager/file_tasks.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/chromeos/file_manager/file_tasks.h"
 
 #include "apps/launcher.h"
 #include "base/bind.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/stringprintf.h"
@@ skipping 33 matching lines @@
 // TODO(satorux): We should rename them to "file_browser_handler" and
 // "file_handler" respectively when switching from preferences to
 // chrome.storage crbug.com/267359
 const char kFileBrowserHandlerTaskType[] = "file";
 const char kFileHandlerTaskType[] = "app";
 const char kDriveAppTaskType[] = "drive";
 
 // Drive apps always use the action ID.
 const char kDriveAppActionID[] = "open-with";
 
-// Default icon path for drive docs.
-const char kDefaultIcon[] = "images/filetype_generic.png";
-
 // Converts a TaskType to a string.
 std::string TaskTypeToString(TaskType task_type) {
   switch (task_type) {
     case TASK_TYPE_FILE_BROWSER_HANDLER:
       return kFileBrowserHandlerTaskType;
     case TASK_TYPE_FILE_HANDLER:
       return kFileHandlerTaskType;
     case TASK_TYPE_DRIVE_APP:
       return kDriveAppTaskType;
     case TASK_TYPE_UNKNOWN:
@@ skipping 464 matching lines @@
     if (file_browser_handlers::IsFallbackFileBrowserHandler(
             task->task_descriptor())) {
       task->set_is_default(true);
       return;
     }
   }
 }
 
 }  // namespace file_tasks
 }  // namespace file_manager