(CANCELED) Improve performance of large option list with CJK text

third_party/WebKit/Source/platform/fonts/Font.cpp

Index: third_party/WebKit/Source/platform/fonts/Font.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/Font.cpp b/third_party/WebKit/Source/platform/fonts/Font.cpp
index 4bcd940b7a38c7f25e67a08897932dc52d4124d4..0a80406f863f471ec96c7ce06445f94e9eaede71 100644
--- a/third_party/WebKit/Source/platform/fonts/Font.cpp
+++ b/third_party/WebKit/Source/platform/fonts/Font.cpp
@@ -239,6 +239,45 @@ float Font::width(const TextRun& run, HashSet<const SimpleFontData*>* fallbackFo
     return floatWidthForSimpleText(run, fallbackFonts, glyphBounds);
 }
 
+float Font::widthForUnbrokenRun(const TextRun& run) const
+{
+    if (run.length() <= 1 || run.is8Bit())
+        return width(run);
+
+    float totalWidth = 0;
+    const unsigned length = run.length();
+    for (unsigned startIndex = 0; startIndex < length; ) {
+        UChar32 ch;
+        unsigned endIndex = startIndex;
+        U16_NEXT(run.characters16(), endIndex, length, ch);
+        if (Character::isCJKIdeographOrSymbol(ch)) {
+            // For scripts that do not delimit words by spaces, split each
+            // character so that input text matches to what the line breaker
+            // requests. This improves the cache efficiency in
+            // CachingWordShaper.
+            for (unsigned i = endIndex; i < length; endIndex = i) {
+                U16_NEXT(run.characters16(), i, length, ch);
+                if (!(U_GET_GC_MASK(ch) & U_GC_M_MASK))
+                    break;
+            }
+        } else {
+            // For scripts that delimit words by spaces, let CachingWordShaper
+            // handle words.
+            for (unsigned i = endIndex; i < length; endIndex = i) {
+                U16_NEXT(run.characters16(), i, length, ch);
+                if (Character::isCJKIdeographOrSymbol(ch))
+                    break;
+            }
+        }
+        if (!startIndex && endIndex == length)
+            return width(run);
+        TextRun subRun = run.subRun(startIndex, endIndex - startIndex);
+        totalWidth += width(subRun);
+        startIndex = endIndex;
+    }
+    return totalWidth;
+}
+
 PassTextBlobPtr Font::buildTextBlob(const GlyphBuffer& glyphBuffer) const
 {
     SkTextBlobBuilder builder;