Create direct write font proxy classes and unit tests.

ui/gfx/win/direct_write.cc

Index: ui/gfx/win/direct_write.cc
diff --git a/ui/gfx/win/direct_write.cc b/ui/gfx/win/direct_write.cc
index 38c926a9bd11da661c3e66b614c177427a6bf6ae..9c8250b5bbf5175e7e339e7b72fbae5cfd550ecd 100644
--- a/ui/gfx/win/direct_write.cc
+++ b/ui/gfx/win/direct_write.cc
@@ -4,8 +4,6 @@
 
 #include "ui/gfx/win/direct_write.h"
 
-#include <dwrite.h>
-
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
@@ -57,12 +55,7 @@ bool ShouldUseDirectWrite() {
   return group_name != "Disabled";
 }
 
-void MaybeInitializeDirectWrite() {
-  static bool tried_dwrite_initialize = false;
-  if (tried_dwrite_initialize)
-    return;
-  tried_dwrite_initialize = true;
-
+void CreateDWriteFactory(IDWriteFactory** factory) {
   if (!ShouldUseDirectWrite() ||
       base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableDirectWriteForUI)) {
@@ -81,13 +74,26 @@ void MaybeInitializeDirectWrite() {
   if (!dwrite_create_factory_proc)
     return;
 
+  // Failure to create the DirectWrite factory indicates a corrupt dll.
+  base::win::ScopedComPtr<IUnknown> factory_unknown;
+  if (FAILED(dwrite_create_factory_proc(DWRITE_FACTORY_TYPE_SHARED,
+                                        __uuidof(IDWriteFactory),
+                                        factory_unknown.Receive()))) {
+    return;
+  }
+  factory_unknown.QueryInterface<IDWriteFactory>(factory);
+}
+
+void MaybeInitializeDirectWrite() {
+  static bool tried_dwrite_initialize = false;
+  if (tried_dwrite_initialize)
+    return;
+  tried_dwrite_initialize = true;
+
   base::win::ScopedComPtr<IDWriteFactory> factory;
+  CreateDWriteFactory(factory.Receive());
 
-  // Failure to create the DirectWrite factory indicates a corrupt dll.
-  if (FAILED(dwrite_create_factory_proc(
-          DWRITE_FACTORY_TYPE_SHARED,
-        __uuidof(IDWriteFactory),
-        reinterpret_cast<IUnknown**>(factory.Receive()))))
+  if (factory == nullptr)
     return;
 
   // The skia call to create a new DirectWrite font manager instance can fail