Provide user friendly messages for OTS parsing of fonts

Source/platform/fonts/FontCustomPlatformData.cpp

Index: Source/platform/fonts/FontCustomPlatformData.cpp
diff --git a/Source/platform/fonts/FontCustomPlatformData.cpp b/Source/platform/fonts/FontCustomPlatformData.cpp
index 1cae8696dde0622b8f6c7993a978996dd3b131e5..39965332afb70e5765fbf3a387f9abb9c686d643 100644
--- a/Source/platform/fonts/FontCustomPlatformData.cpp
+++ b/Source/platform/fonts/FontCustomPlatformData.cpp
@@ -85,14 +85,19 @@ FontPlatformData FontCustomPlatformData::fontPlatformData(float size, bool bold,
     return FontPlatformData(m_typeface.get(), "", size, bold && !m_typeface->isBold(), italic && !m_typeface->isItalic(), orientation);
 }
 
-PassOwnPtr<FontCustomPlatformData> FontCustomPlatformData::create(SharedBuffer* buffer)
+PassOwnPtr<FontCustomPlatformData> FontCustomPlatformData::create(SharedBuffer* buffer, String& otsParseMessage)
 {
     ASSERT_ARG(buffer, buffer);
 
     OpenTypeSanitizer sanitizer(buffer);
     RefPtr<SharedBuffer> transcodeBuffer = sanitizer.sanitize();
-    if (!transcodeBuffer)
+
+    if (!transcodeBuffer || sanitizer.isParsingError()) {
+        if (sanitizer.isParsingError())

[jungshik at Google, 2015/05/12 20:22:48]

I wonder if there's a case when transcodeBuffer==0 but isParsingError() = false.
 If not, we can have just a single if-stmnt. 

[h.joshi, 2015/05/14 04:52:15]

Yes, two checks are not required. thank you.
Made changes. 

+            otsParseMessage = sanitizer.getErrorString();
+
         return nullptr; // validation failed.
+    }
     buffer = transcodeBuffer.get();
 
     SkMemoryStream* stream = new SkMemoryStream(buffer->getAsSkData().get());