blink fonts: Load Android SkFontMgr on Linux.

third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp

Index: third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp b/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
index d9af8814f20745f374402948176848edc5db9597..5d6f98beecec62d80c408c1c5298d33e68a163ee 100644
--- a/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
+++ b/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
@@ -31,6 +31,7 @@
 #include "SkFontMgr.h"
 #include "SkStream.h"
 #include "SkTypeface.h"
+#include "platform/Language.h"
 #include "platform/fonts/AlternateFontFamily.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontDescription.h"
@@ -87,6 +88,51 @@ static PassRefPtr<SkTypeface> typefaceForFontconfigInterfaceIdAndTtcIndex(int fo
 
 namespace blink {
 
+// SkFontMgr requires script-based locale names, like "zh-Hant" and "zh-Hans",
+// instead of "zh-CN" and "zh-TW".
+static CString toSkFontMgrLocale(const String& locale)
+{
+    if (!locale.startsWith("zh", TextCaseInsensitive))
+        return locale.ascii();
+
+    switch (localeToScriptCodeForFontSelection(locale)) {
+    case USCRIPT_SIMPLIFIED_HAN:
+        return "zh-Hans";
+    case USCRIPT_TRADITIONAL_HAN:
+        return "zh-Hant";
+    default:
+        return locale.ascii();
+    }
+}
+
+
+#if OS(ANDROID) || OS(LINUX)
+// This function is called on android or when we are emulating android fonts on linux and the
+// embedder has overriden the default fontManager with WebFontRendering::setSkiaFontMgr.
+// static
+AtomicString FontCache::getFamilyNameForCharacter(SkFontMgr* fm, UChar32 c, const FontDescription& fontDescription)
+{
+    ASSERT(fm);
+
+    const char* bcp47Locales[2];
+    int localeCount = 0;
+    CString defaultLocale = toSkFontMgrLocale(defaultLanguage());
+    bcp47Locales[localeCount++] = defaultLocale.data();
+    CString fontLocale;
+    if (!fontDescription.locale().isEmpty()) {
+        fontLocale = toSkFontMgrLocale(fontDescription.locale());
+        bcp47Locales[localeCount++] = fontLocale.data();
+    }
+    RefPtr<SkTypeface> typeface = adoptRef(fm->matchFamilyStyleCharacter(0, SkFontStyle(), bcp47Locales, localeCount, c));
+    if (!typeface)
+        return emptyAtom;
+
+    SkString skiaFamilyName;
+    typeface->getFamilyName(&skiaFamilyName);
+    return skiaFamilyName.c_str();
+}
+#endif
+
 void FontCache::platformInit()
 {
 }
@@ -113,6 +159,19 @@ PassRefPtr<SimpleFontData> FontCache::fallbackOnStandardFontStyle(
 #if !OS(WIN) && !OS(ANDROID)
 PassRefPtr<SimpleFontData> FontCache::fallbackFontForCharacter(const FontDescription& fontDescription, UChar32 c, const SimpleFontData*)
 {
+#if OS(LINUX)
+    // On linux the m_fontManager is set only if it was provided by the embedder with WebFontRendering::setSkiaFontManager. This is
+    // used to emulate android fonts so we always request the family from the font manager and if none is found, we return
+    // the LastResort fallback font and avoid using FontCache::getFontForCharacter which would use sandbox support to
+    // query the underlying system for the font family.
+    if (m_fontManager) {
+        AtomicString familyName = getFamilyNameForCharacter(m_fontManager.get(), c, fontDescription);
+        if (familyName.isEmpty())
+            return getLastResortFallbackFont(fontDescription, DoNotRetain);
+        return fontDataFromFontPlatformData(getFontPlatformData(fontDescription, FontFaceCreationParams(familyName)), DoNotRetain);
+    }
+#endif
+
     // First try the specified font with standard style & weight.
     if (fontDescription.style() == FontStyleItalic
         || fontDescription.weight() >= FontWeight600) {
@@ -277,6 +336,14 @@ PassRefPtr<SkTypeface> FontCache::createTypeface(const FontDescription& fontDesc
     }
 #endif
 
+#if OS(LINUX)
+    // On linux if the fontManager has been overridden then we should be calling the embedder
+    // provided font Manager rather than calling SkTypeface::CreateFromName which may redirect the
+    // call to the default font Manager.
+    if (m_fontManager)
+        return adoptRef(m_fontManager->legacyCreateTypeface(name.data(), style));
+#endif
+
     // FIXME: Use m_fontManager, SkFontStyle and matchFamilyStyle instead of
     // CreateFromName on all platforms.
     return adoptRef(SkTypeface::CreateFromName(name.data(), static_cast<SkTypeface::Style>(style)));