Add plumbing in blink to allow overriding the skia font manager.

third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp

Index: third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp b/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
index 9e2f7619b4f1354be3089543ae8859c1a46f10c1..92e7188178d7a40b4789aeb7a244ac3585707e46 100644
--- a/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
+++ b/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
@@ -97,19 +97,18 @@ void FontCache::setStatusFontMetrics(const wchar_t* familyName, int32_t fontHeig
 FontCache::FontCache()
     : m_purgePreventCount(0)
 {
-    SkFontMgr* fontManager;
-
-    if (s_useDirectWrite) {
-        fontManager = SkFontMgr_New_DirectWrite(s_directWriteFactory);
-        s_useSubpixelPositioning = true;
+    if (s_fontManager) {
+        m_fontManager = s_fontManager;
+    } else if (s_useDirectWrite) {
+        m_fontManager = adoptRef(SkFontMgr_New_DirectWrite());
     } else {
-        fontManager = SkFontMgr_New_GDI();
-        // Subpixel text positioning is not supported by the GDI backend.
-        s_useSubpixelPositioning = false;
+        m_fontManager = adoptRef(SkFontMgr_New_GDI());
     }
 
-    ASSERT(fontManager);
-    m_fontManager = adoptPtr(fontManager);
+    // Subpixel text positioning is only supported by the DirectWrite backend (not GDI).
+    s_useSubpixelPositioning = s_useDirectWrite;
+
+    ASSERT(m_fontManager.get());
 }
 
 void FontCache::acceptLanguagesChanged(const String&)