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 0564687282805a3959bc4f44b00890e0b0d196c2..b3e4eaf4e6529b167493d31fc3f663175d85e692 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 = skia::SharePtr(s_fontManager);
+    } else if (s_useDirectWrite) {
+        m_fontManager = skia::AdoptRef(SkFontMgr_New_DirectWrite(s_directWriteFactory));

[bungeman-chromium, 2016/01/21 15:48:13]

This appears to be the only place s_directWriteFactory is used. It appears that
with this code change this branch will never be taken, so s_directWriteFactory
and related should be removed.

[Ilya Kulshin, 2016/01/21 20:59:22]

s_useDirectWrite is set via setUseDirectWrite, which is still called from
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/r...
and
https://code.google.com/p/chromium/codesearch#chromium/src/content/ppapi_plug....
setDirectWriteFactory can still be called from
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/fon...,
which is called if ShouldUseDirectWriteFontProxyFieldTrial returns false. For
now, it is still needed, but I will make a note to remove it when deleting the
old chrome font cache codepath.

[bungeman-skia, 2016/01/21 21:11:40]

Sure, s_useDirectWrite is still called (and should also be removed) but you'll
still never get here, because every path which will set it to true will also
already have set the s_fontManager (and if it doesn't, it should be).

In other words, this CL is adding code to support s_directWriteFactory and
s_useDirectWrite, but it doesn't seem that this is necessary (or wanted).

     } else {
-        fontManager = SkFontMgr_New_GDI();
-        // Subpixel text positioning is not supported by the GDI backend.
-        s_useSubpixelPositioning = false;
+        m_fontManager = skia::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());
 }