Allow the default generic font family settings to find the first available font

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

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 30 matching lines @@
 #include "platform/fonts/FontDescription.h"
 #include "platform/fonts/FontPlatformData.h"
 #include "platform/fonts/FontSmoothingMode.h"
 #include "platform/fonts/SimpleFontData.h"
 #include "platform/fonts/TextRenderingMode.h"
 #include "platform/fonts/opentype/OpenTypeVerticalData.h"
 #include "platform/fonts/shaping/ShapeCache.h"
 #include "platform/tracing/web_memory_allocator_dump.h"
 #include "platform/tracing/web_process_memory_dump.h"
 #include "public/platform/Platform.h"
+#include "ui/gfx/font.h"
 #include "wtf/HashMap.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicStringHash.h"
 #include "wtf/text/StringHash.h"
 #include <memory>
 
 using namespace WTF;
@@ skipping 235 matching lines @@
 
 bool FontCache::isPlatformFontAvailable(const FontDescription& fontDescription,
                                         const AtomicString& family) {
   bool checkingAlternateName = true;
   return getFontPlatformData(
       fontDescription,
       FontFaceCreationParams(adjustFamilyNameToAvoidUnsupportedFonts(family)),
       checkingAlternateName);
 }
 
+String FontCache::firstAvailableOrFirst(const String& families) {
+  return String::fromUTF8(

[eae, 2016/10/26 16:59:36]

I don't suppose we could change gfx::Font::FirstAvailableOrFirst to take a
utf-16 string? If not this is fine but please add a comment explaining the
conversions.

[kojii, 2016/10/28 05:07:14]

I think it's possible, but after looking into it, I think it doesn't help much.
The only input string as of now are all ASCII, and gfx::Font needs to convert
the inputs to UTF-8 when it calls Skia. So from the perf perspective, the ideal
thing is gfx::Font::FirstAvailableOrFirst to have Latin1 string to avoid string
copies and convert between ASCII/UTF-8, but it looks like too specific.

GenericFontFamilySettings caches the result, so this is called at most 1 or 2
times per renderer/setting change/script, and probably only for a few scripts. I
think we're ok for now, and if the usage increases, I'm happy to look into
further to avoid the conversions and copies.

Added comment.

+      gfx::Font::FirstAvailableOrFirst(families.utf8().data()).c_str());
+}
+
 SimpleFontData* FontCache::getNonRetainedLastResortFallbackFont(
     const FontDescription& fontDescription) {
   return getLastResortFallbackFont(fontDescription, DoNotRetain).leakRef();
 }
 
 void FontCache::releaseFontData(const SimpleFontData* fontData) {
   ASSERT(gFontDataCache);
 
   gFontDataCache->release(fontData);
 }
@@ skipping 158 matching lines @@
   for (iter = gFallbackListShaperCache->begin();
        iter != gFallbackListShaperCache->end(); ++iter) {
     shapeResultCacheSize += iter->value->byteSize();
   }
   dump->AddScalar("size", "bytes", shapeResultCacheSize);
   memoryDump->AddSuballocation(dump->guid(),
                                WTF::Partitions::kAllocatedObjectPoolName);
 }
 
 }  // namespace blink