Fix DM build failures:
  - forgot tool_main;
  - skip building where skia_gpu is false;
  - lots of scalar -> int warnings;
  - stray return on a void method;
  - stifle warning about a uint32_t cast to bool

BUG=
R=bungeman@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/26468005

git-svn-id: http://skia.googlecode.com/svn/trunk@11821 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed