Mojo: Fix possibly-invalid vector subscripting in RawChannelPosix.

In RawChannelPosix::OnFileCanReadWithoutBlocking()'s call to memmove(),
read_buffer_start may point one past the end of the buffer. This isn't a
"real" problem, since in that case read_buffer_num_valid_bytes_ will be
zero, but it's illegal to subscript a vector with an invalid index and
an assertion fails in Debug builds (an alternate fix would be to replace
&read_buffer_[read_buffer_start] with &read_buffer_[0] +
read_buffer_start).

The bug was exhibited by the flakily-failing
MultiprocessMessagePipeTest.QueueMessages (in Debug builds), so to test
run:

out/Debug/mojo_system_unittests \
    --gtest_filter=MultiprocessMessagePipeTest.QueueMessages \
    --gtest_repeat=-1 --single-process-tests

R=darin@chromium.org
BUG=329622

Review URL: https://codereview.chromium.org/132173003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244194 0039d316-1c4b-4281-b951-d872f2087c98
Add fontconfig directory & ignore "src" subdirectory


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244195 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244195
Remove PrerenderTracker::TryCancel* methods and associated ones, since destruction of prerender only happens on the UI thread through PrerenderContents now.

BUG=304341
R=mmenke@chromium.org, tburkard@chromium.org

Review URL: https://codereview.chromium.org/132613002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244196 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244196