Make skpinfo able to inspect SK_PICT_TYPEFACE_TAG blocks

src/core/SkFontDescriptor.cpp

Index: src/core/SkFontDescriptor.cpp
diff --git a/src/core/SkFontDescriptor.cpp b/src/core/SkFontDescriptor.cpp
index 8348d5fdba44ce16451964eb43fc31e9fc40f886..69001ae418c9bf031ef2e2da5916b4af6fdcd4e1 100644
--- a/src/core/SkFontDescriptor.cpp
+++ b/src/core/SkFontDescriptor.cpp
@@ -58,8 +58,8 @@ static void write_uint(SkWStream* stream, size_t n, uint32_t id) {
     stream->writePackedUInt(n);
 }
 
-SkFontDescriptor::SkFontDescriptor(SkStream* stream) {
-    fStyle = (SkTypeface::Style)stream->readPackedUInt();
+bool SkFontDescriptor::Deserialize(SkStream* stream, SkFontDescriptor* result) {
+    result->fStyle = (SkTypeface::Style)stream->readPackedUInt();
 
     SkAutoSTMalloc<4, SkFixed> axis;
     size_t axisCount = 0;
@@ -67,13 +67,13 @@ SkFontDescriptor::SkFontDescriptor(SkStream* stream) {
     for (size_t id; (id = stream->readPackedUInt()) != kSentinel;) {
         switch (id) {
             case kFontFamilyName:
-                read_string(stream, &fFamilyName);
+                read_string(stream, &result->fFamilyName);
                 break;
             case kFullName:
-                read_string(stream, &fFullName);
+                read_string(stream, &result->fFullName);
                 break;
             case kPostscriptName:
-                read_string(stream, &fPostscriptName);
+                read_string(stream, &result->fPostscriptName);
                 break;
             case kFontAxes:
                 axisCount = read_uint(stream);
@@ -90,7 +90,7 @@ SkFontDescriptor::SkFontDescriptor(SkStream* stream) {
                 break;
             default:
                 SkDEBUGFAIL("Unknown id used by a font descriptor");
-                return;
+                return false;
         }
     }
 
@@ -98,9 +98,13 @@ SkFontDescriptor::SkFontDescriptor(SkStream* stream) {
     if (length > 0) {
         SkAutoTUnref<SkData> data(SkData::NewUninitialized(length));
         if (stream->read(data->writable_data(), length) == length) {
-            fFontData.reset(new SkFontData(new SkMemoryStream(data), index, axis, axisCount));
+            result->fFontData.reset(new SkFontData(new SkMemoryStream(data),
+                                                   index, axis, axisCount));
+        } else {
+            return false;

[bungeman-skia, 2016/02/25 15:41:17]

For consistency with the above 'default' handling, a SkDEBUGFAIL("Could not read
font data.") should go before the return, so that at least in debug we die early
with a more specific message. Note that this probably means removing the
SkDEBUGFAIL in SkTypeface.cpp and SkWhitelistTypeface.cpp below, since they'll
never actually happen (and their message is more generic in any event). In
general, this seems to point out the general lack of error reporting or recovery
in this whole mechanism.

[robertphillips, 2016/02/25 15:53:22]

Done.

         }
     }
+    return true;
 }
 
 void SkFontDescriptor::serialize(SkWStream* stream) {