Add a new feature define ENABLE_BLOB.
Add a new feature define ENABLE_BLOB.

We need to replace all blob related feature defines ENABLE_BLOB_SLICE and
ENABLE_FILE_READER. This patch only adds the new feature define in order to be
prepared for the corresponding WebKit patch to land. After it is brought down,
we will then remove 2 obsolete feature defines.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/3082001

git-svn-id: http://src.chromium.org/svn/trunk/src@54770 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 8495c54793d0f610e4963fc5caa23bcca724ed09
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser