Add plumbing in blink to allow overriding the default font collection.

content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.cc

 // 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.
 
 #include "content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h"
 
 #include <dwrite.h>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/debug/alias.h"
 #include "base/win/iat_patch_function.h"
 #include "base/win/windows_version.h"
 #include "content/child/dwrite_font_proxy/dwrite_font_proxy_win.h"
 #include "content/common/font_warmup_win.h"
 #include "skia/ext/fontmgr_default_win.h"
+#include "skia/ext/refptr.h"
 #include "third_party/WebKit/public/web/win/WebFontRendering.h"
 #include "third_party/skia/include/ports/SkTypeface_win.h"
 
 namespace mswr = Microsoft::WRL;
 
 namespace content {
 
 namespace {
 
 mswr::ComPtr<DWriteFontCollectionProxy> g_font_collection;
@@ skipping 24 matching lines @@
     DWORD get_proc_address_get_last_error = GetLastError();
     base::debug::Alias(&dwrite_create_factory_proc);
     base::debug::Alias(&get_proc_address_get_last_error);
     CHECK(false);
   }
   CHECK(SUCCEEDED(dwrite_create_factory_proc(
       DWRITE_FACTORY_TYPE_ISOLATED, __uuidof(IDWriteFactory),
       reinterpret_cast<IUnknown**>(factory))));
 }
 
-HRESULT STDMETHODCALLTYPE StubFontCollection(IDWriteFactory* factory,
-                                             IDWriteFontCollection** col,
-                                             BOOL checkUpdates) {
-  DCHECK(g_font_collection);
-  g_font_collection.CopyTo(col);
-  return S_OK;
-}
-
-// Copied from content/common/font_warmup_win.cc
-void PatchDWriteFactory(IDWriteFactory* factory) {
-  const unsigned int kGetSystemFontCollectionVTableIndex = 3;
-
-  PROC* vtable = *reinterpret_cast<PROC**>(factory);
-  PROC* function_ptr = &vtable[kGetSystemFontCollectionVTableIndex];
-  void* stub_function = &StubFontCollection;
-  base::win::ModifyCode(function_ptr, &stub_function, sizeof(PROC));
-}
-
 // Needed as a function for Bind()
 IPC::Sender* GetSenderOverride() {
   return g_sender_override;
 }
 
 }  // namespace
 
 void InitializeDWriteFontProxy(
     const base::Callback<IPC::Sender*(void)>& sender) {
   mswr::ComPtr<IDWriteFactory> factory;
 
   CreateDirectWriteFactory(&factory);
 
   if (!g_font_collection) {
     if (g_sender_override) {
       mswr::MakeAndInitialize<DWriteFontCollectionProxy>(
           &g_font_collection, factory.Get(), base::Bind(&GetSenderOverride));
     } else {
       mswr::MakeAndInitialize<DWriteFontCollectionProxy>(&g_font_collection,
                                                          factory.Get(), sender);
     }
   }
 
-  PatchDWriteFactory(factory.Get());
+  skia::RefPtr<SkFontMgr> skia_font_manager = skia::AdoptRef(
+      SkFontMgr_New_DirectWrite(factory.Get(), g_font_collection.Get()));
+  blink::WebFontRendering::setSkiaFontManager(skia_font_manager);
 
-  blink::WebFontRendering::setDirectWriteFactory(factory.Get());
-  SkFontMgr* skia_font_manager = SkFontMgr_New_DirectWrite(factory.Get());
-  SetDefaultSkiaFactory(skia_font_manager);
+  // Add an extra ref for SetDefaultSkiaFactory, which keeps a ref but doesn't
+  // addref.
+  skia_font_manager->ref();
+  SetDefaultSkiaFactory(skia_font_manager.get());
 }
 
 void UninitializeDWriteFontProxy() {
   if (g_font_collection)
     g_font_collection->Unregister();
 }
 
 void SetDWriteFontProxySenderForTesting(IPC::Sender* sender) {
   g_sender_override = sender;
 }
 
 }  // namespace content