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

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 b34762474b583cb88d8e45eb0babd6413200017a..0c4ef28ceff35ebc4692549cea495e3165e966a4 100644
--- a/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
+++ b/third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp
@@ -97,19 +97,19 @@ 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) {
+        adopted(s_fontManager);

[bungeman-chromium, 2016/02/09 22:25:17]

The adoption checks are only done in debug, so 'adopted' only exists in debug.

[jbroman, 2016/02/09 22:31:30]

Well, it does exist here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
as long as PassRefPtr.h is included, and this is called as WTF::adopted (I don't
think ADL will work here?), this should work?

[bungeman-chromium, 2016/02/09 22:36:05]

Note that adding 'using WTF::adopted' should work to fix release. I haven't
verified that though (or if that is a good idea). This is being provided in
debug from sk_ref_cnt_ext_debug.h (and isn't from sk_ref_cnt_ext_release.h). I
would rely on someone more familiar with Blink's reference counting for real
advice though.

This seems to be complicated by the 'rel' trybots actually being 'debug with
optimizations' as opposed to the 'rel' bots on the waterfall which are actually
'release'.

+        m_fontManager = s_fontManager;
+    } else if (s_useDirectWrite) {
+        m_fontManager = adoptRef(SkFontMgr_New_DirectWrite());

[bungeman-chromium, 2016/02/04 21:40:32]

I'm assuming this is only true then not running in the sandbox.

[Ilya Kulshin, 2016/02/05 02:02:47]

Yes, I believe this case only happens during tests when not using the sandbox.
This codepath would not work if run during the sandbox (we would be unable to
get any fonts).

     } 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());
 }