Clean up the IconLoader.

chrome/browser/icon_loader_auralinux.cc

 // Copyright 2013 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/icon_loader.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/nix/mime_util_xdg.h"
 #include "ui/views/linux_ui/linux_ui.h"
 
 // static
-IconGroupID IconLoader::ReadGroupIDFromFilepath(
+IconLoader::IconGroup IconLoader::GroupForFilepath(
     const base::FilePath& filepath) {
   return base::nix::GetFileMimeType(filepath);

[sky, 2016/10/24 15:56:25]

I believe this may trigger io:
std::string GetFileMimeType(const FilePath& filepath) {
  ...
  ThreadRestrictions::AssertIOAllowed();

AFAICT you call this from LookupIconFromFilepath, which I believe is meant to be
called from the main thread.

[Avi (use Gerrit), 2016/10/24 16:02:18]

:( Missed that platform. Let me try again.

 }
 
 // static
-bool IconLoader::IsIconMutableFromFilepath(const base::FilePath&) {
-  return false;
-}
-
-// static
 content::BrowserThread::ID IconLoader::ReadIconThreadID() {
   // ReadIcon() calls into views::LinuxUI and GTK2 code, so it must be on the UI
   // thread.
   return content::BrowserThread::UI;
 }
 
 void IconLoader::ReadIcon() {
   int size_pixels = 0;
   switch (icon_size_) {
     case IconLoader::SMALL:
@@ skipping 12 matching lines @@
   views::LinuxUI* ui = views::LinuxUI::instance();
   if (ui) {
     gfx::Image image = ui->GetIconForContentType(group_, size_pixels);
     if (!image.IsEmpty())
       image_.reset(new gfx::Image(image));
   }
 
   target_task_runner_->PostTask(
       FROM_HERE, base::Bind(&IconLoader::NotifyDelegate, this));
 }