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

content/public/renderer/render_thread.h

Index: content/public/renderer/render_thread.h
diff --git a/content/public/renderer/render_thread.h b/content/public/renderer/render_thread.h
index 002f45d04603caf54824bc2ad9c817dc791a6e18..407128b33313dcb4be77e7a2815260d9c5721bf9 100644
--- a/content/public/renderer/render_thread.h
+++ b/content/public/renderer/render_thread.h
@@ -10,12 +10,8 @@
 #include "base/memory/shared_memory.h"
 #include "base/metrics/user_metrics_action.h"
 #include "content/common/content_export.h"
+#include "content/public/child/child_thread.h"
 #include "ipc/ipc_channel_proxy.h"
-#include "ipc/ipc_sender.h"
-
-#if defined(OS_WIN)
-#include <windows.h>
-#endif
 
 class GURL;
 
@@ -45,7 +41,7 @@ class RenderProcessObserver;
 class ResourceDispatcherDelegate;
 class ServiceRegistry;
 
-class CONTENT_EXPORT RenderThread : public IPC::Sender {
+class CONTENT_EXPORT RenderThread : virtual public ChildThread {
  public:
   // Returns the one render thread for this process.  Note that this can only
   // be accessed when running on the render thread itself.
@@ -135,15 +131,6 @@ class CONTENT_EXPORT RenderThread : public IPC::Sender {
   // Gets the shutdown event for the process.
   virtual base::WaitableEvent* GetShutdownEvent() = 0;
 
-#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
-
   // Returns the ServiceRegistry for this thread.
   virtual ServiceRegistry* GetServiceRegistry() = 0;
 };