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

content/gpu/gpu_child_thread.h

Index: content/gpu/gpu_child_thread.h
diff --git a/content/gpu/gpu_child_thread.h b/content/gpu/gpu_child_thread.h
index b5c312db9353d44396cf9d15b2558c18d8235283..7103cd3034c960b34c214e213f2c6dd392710fb6 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -14,7 +14,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
-#include "content/child/child_thread.h"
+#include "content/child/child_thread_impl.h"
 #include "content/common/gpu/gpu_channel.h"
 #include "content/common/gpu/gpu_channel_manager.h"
 #include "content/common/gpu/gpu_config.h"
@@ -33,7 +33,7 @@ class GpuWatchdogThread;
 // these per process. It does process initialization and shutdown. It forwards
 // IPC messages to GpuChannelManager, which is responsible for issuing rendering
 // commands to the GPU.
-class GpuChildThread : public ChildThread {
+class GpuChildThread : public ChildThreadImpl {
  public:
   typedef std::queue<IPC::Message*> DeferredMessages;