Add UMA for hb_face_t instantiation type

third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzFace.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "platform/fonts/shaping/HarfBuzzFace.h"
 
+#include "platform/Histogram.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontPlatformData.h"
 #include "platform/fonts/SimpleFontData.h"
 #include "platform/fonts/UnicodeRangeSet.h"
 #include "platform/fonts/shaping/HarfBuzzShaper.h"
 #include "wtf/HashMap.h"
 #include "wtf/MathExtras.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 #include <hb-ot.h>
 #include <hb.h>
 #if OS(MACOSX)
 #include <hb-coretext.h>
 #endif
 
 #include <SkPaint.h>
 #include <SkPath.h>
 #include <SkPoint.h>
 #include <SkRect.h>
 #include <SkStream.h>
 #include <SkTypeface.h>
 
 
 namespace blink {
 
+enum HarfBuzzFaceInstantiationTypeUMA {

[Mark P, 2016/06/27 21:28:41]

Please put the standard warning here that these values are written to logs and
should not be renumbered or deleted.

Or, why is this an enumerated histogram rather than simply a BooleanHistogram? 
Do you expect to expand it later?

[drott, 2016/06/28 07:38:47]

I was initially considering reporting the different instantiation type on Mac,
but that's unrelated, so I am switching to BooleanSuccess.

+    HarfBuzzFaceInstantiationTypeInplace = 0,
+    HarfBuzzFaceInstantiationTypeTableCopy,
+    MaxHarfBuzzFaceInstantiationType
+};
+
 struct HbFontDeleter {
     void operator()(hb_font_t* font)
     {
         if (font)
             hb_font_destroy(font);
     }
 };
 
 using HbFontUniquePtr = std::unique_ptr<hb_font_t, HbFontDeleter>;
 
@@ skipping 251 matching lines @@
 }
 #endif
 
 hb_face_t* HarfBuzzFace::createFace()
 {
 #if OS(MACOSX)
     hb_face_t* face = hb_coretext_face_create(m_platformData->cgFont());
 #else
     hb_face_t* face = nullptr;
 
+    DEFINE_STATIC_LOCAL(EnumerationHistogram,
+        faceInstantiationHistogram,
+        ("Blink.Fonts.HarfBuzzFaceInstantiationType", MaxHarfBuzzFaceInstantiationType));
     SkTypeface* typeface = m_platformData->typeface();
     int ttcIndex = 0;
     SkStreamAsset* typefaceStream = typeface->openStream(&ttcIndex);
     if (typefaceStream->getMemoryBase()) {
         std::unique_ptr<hb_blob_t, void(*)(hb_blob_t*)> faceBlob(hb_blob_create(
             reinterpret_cast<const char*>(typefaceStream->getMemoryBase()),
             typefaceStream->getLength(),
             HB_MEMORY_MODE_READONLY,
             typefaceStream,
             deleteTypefaceStream),
             hb_blob_destroy);
         face = hb_face_create(faceBlob.get(), ttcIndex);
     }
 
     // Fallback to table copies if there is no in-memory access.
-    if (!face)
+    if (!face) {
         face = hb_face_create_for_tables(harfBuzzSkiaGetTable, m_platformData->typeface(), 0);
+        faceInstantiationHistogram.count(HarfBuzzFaceInstantiationTypeTableCopy);
+    } else {
+        faceInstantiationHistogram.count(HarfBuzzFaceInstantiationTypeInplace);
+    }
 #endif
     ASSERT(face);
     return face;
 }
 
 PassRefPtr<HbFontCacheEntry> createHbFontCacheEntry(hb_face_t* face)
 {
     HbFontUniquePtr otFont(hb_font_create(face));
     hb_ot_font_set_funcs(otFont.get());
     // Creating a sub font means that non-available functions
     // are found from the parent.
     hb_font_t* unscaledFont = hb_font_create_sub_font(otFont.get());
     RefPtr<HbFontCacheEntry> cacheEntry = HbFontCacheEntry::create(unscaledFont);
     hb_font_set_funcs(unscaledFont, harfBuzzSkiaGetFontFuncs(), cacheEntry->hbFontData(), nullptr);
     return cacheEntry;
 }
 
 hb_font_t* HarfBuzzFace::getScaledFont(PassRefPtr<UnicodeRangeSet> rangeSet) const
 {
     m_platformData->setupPaint(&m_harfBuzzFontData->m_paint);
     m_harfBuzzFontData->m_rangeSet = rangeSet;
     m_harfBuzzFontData->m_simpleFontData = FontCache::fontCache()->fontDataFromFontPlatformData(m_platformData).get();
     ASSERT(m_harfBuzzFontData->m_simpleFontData);
     int scale = SkiaScalarToHarfBuzzPosition(m_platformData->size());
     hb_font_set_scale(m_unscaledFont, scale, scale);
     return m_unscaledFont;
 }
 
 } // namespace blink