Add logic to switch to DirectWrite font proxy via field trial.

content/public/common/dwrite_font_platform_win.h

Index: content/public/common/dwrite_font_platform_win.h
diff --git a/content/public/common/dwrite_font_platform_win.h b/content/public/common/dwrite_font_platform_win.h
index 4c988bc82eb20acc970f6eba10bcd2547fc4f7e0..d1b1eff6bac9c33500f709b43ac3f33601307968 100644
--- a/content/public/common/dwrite_font_platform_win.h
+++ b/content/public/common/dwrite_font_platform_win.h
@@ -36,6 +36,12 @@ CONTENT_EXPORT bool LoadFontCache(const base::FilePath& path);
 // Added in header mainly for unittest
 CONTENT_EXPORT bool ValidateFontCacheFile(base::File* file);
 
+// Determines whether code should use the DirectWrite font proxy codepathh.

[fdoray, 2015/12/30 01:15:08]

*codepath

[Ilya Kulshin, 2015/12/30 01:59:46]

Done.

+// Note that this function only checks whether the field trial is enabled.
+// Callers are still expected to take appropriate action based on the return
+// value.
+CONTENT_EXPORT bool ShouldUseDirectWriteFontProxyFieldTrial();
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_DWRITE_FONT_PLATFORM_WIN_H_