Create direct write font proxy classes and unit tests.

ui/gfx/win/direct_write.cc

 // Copyright 2014 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 "ui/gfx/win/direct_write.h"
 
-#include <dwrite.h>
-
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/win/registry.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/windows_version.h"
 #include "skia/ext/fontmgr_default_win.h"
 #include "third_party/skia/include/ports/SkTypeface_win.h"
 #include "ui/gfx/platform_font_win.h"
 #include "ui/gfx/switches.h"
@@ skipping 31 matching lines @@
   // Can't use GDI on HiDPI.
   if (gfx::GetDPIScale() > 1.0f)
     return true;
 
   // Otherwise, check the field trial.
   const std::string group_name =
       base::FieldTrialList::FindFullName("DirectWrite");
   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)) {
     return;
   }
 
   using DWriteCreateFactoryProc = decltype(DWriteCreateFactory)*;
   HMODULE dwrite_dll = LoadLibraryW(L"dwrite.dll");
   if (!dwrite_dll)
     return;
 
   DWriteCreateFactoryProc dwrite_create_factory_proc =
       reinterpret_cast<DWriteCreateFactoryProc>(
           GetProcAddress(dwrite_dll, "DWriteCreateFactory"));
   // Not finding the DWriteCreateFactory function indicates a corrupt dll.
   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
   // if we are unable to get the system font collection from the DirectWrite
   // factory. The GetSystemFontCollection method in the IDWriteFactory
   // interface fails with E_INVALIDARG on certain Windows 7 gold versions
   // (6.1.7600.*). We should just use GDI in these cases.
   SkFontMgr* direct_write_font_mgr = SkFontMgr_New_DirectWrite(factory.get());
   if (!direct_write_font_mgr)
     return;
   dwrite_enabled = true;
   SetDefaultSkiaFactory(direct_write_font_mgr);
   gfx::PlatformFontWin::SetDirectWriteFactory(factory.get());
 }
 
 bool IsDirectWriteEnabled() {
   return dwrite_enabled;
 }
 
 }  // namespace win
 }  // namespace gfx