Unify the three places that patch font loading for PDFium on Windows.

content/public/child/child_thread.h

+// 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.
+
+#ifndef CONTENT_PUBLIC_CHILD_THREAD_H_
+#define CONTENT_PUBLIC_CHILD_THREAD_H_
+
+#include "content/common/content_export.h"
+#include "ipc/ipc_sender.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#endif
+
+namespace content {
+
+class CONTENT_EXPORT ChildThread : public IPC::Sender {
+ public:
+  // Returns the one child thread for this process.  Note that this can only be
+  // accessed when running on the child thread itself.
+  static ChildThread* Get();
+
+  ~ChildThread() override {}
+
+#if defined(OS_WIN)
+  // Request that the given font be loaded by the browser so it's cached by the
+  // OS. Please see ChildProcessHost::PreCacheFont for details.
+  virtual void PreCacheFont(const LOGFONT& log_font) = 0;
+
+  // Release cached font.
+  virtual void ReleaseCachedFonts() = 0;
+#endif
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_CHILD_THREAD_H_