Initial error handling code

I made it as simple as possible. The impact seems minimal and it should do what's necessary to make this code secure.

BUG=

Committed: http://code.google.com/p/skia/source/detail?r=11247

R=reed@google.com, scroggo@google.com, djsollen@google.com, sugoi@google.com, bsalomon@google.com, mtklein@google.com, senorblanco@google.com, senorblanco@chromium.org

Author: sugoi@chromium.org

Review URL: https://codereview.chromium.org/23021015

git-svn-id: http://skia.googlecode.com/svn/trunk@11922 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/core.gypi b/gyp/core.gypi
index e6a7a44..5be1ead 100644
--- a/gyp/core.gypi
+++ b/gyp/core.gypi
@@ -195,6 +195,7 @@
         '<(skia_src_path)/core/SkTypefaceCache.h',
         '<(skia_src_path)/core/SkUnPreMultiply.cpp',
         '<(skia_src_path)/core/SkUtils.cpp',
+        '<(skia_src_path)/core/SkValidatingReadBuffer.cpp',
         '<(skia_src_path)/core/SkWriter32.cpp',
         '<(skia_src_path)/core/SkXfermode.cpp',