Fixing gcc 4.7 building problems.

a) - gcc-4.7 improved the implicit headers that it includes. with
<4.7, the gthr-default.h file always pulls in unistd.h. with >=4.7,
they avoided that include when possible. so code that isn't including
unistd.h itself but needs it now breaks.

b) - narrowing conversion in initiliazation list now raises an
'ill-formed conversion' warning, which causes error when -Werror is
given.

[THIS PART IS NOW REVERTED IN THE PATCH} c) - included patches from pastebin - http://pastebin.com/raw.php?i=p3UKs7Cg

Note - this may not be fixing all the gcc 4.7 build problems for all
parts, but rather than submitting one big-fix-for-all CL, we'd better
do it incrementally (given that all the modification is reasonable and
minor) so that at least some parts get a successful gcc 4.7 build.

BUG=None
TEST=Built successfully using GCC-4.7 under chromium chroot


Review URL: https://chromiumcodereview.appspot.com/10451068

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@140470 0039d316-1c4b-4281-b951-d872f2087c98

• base/time_posix.cc[diff]
• chrome/browser/chromeos/process_proxy/process_output_watcher.cc[diff]
• chrome/browser/extensions/settings/settings_frontend.cc[diff]
• chrome/browser/policy/policy_path_parser_linux.cc[diff]
• content/public/common/sandbox_init.cc[diff]
• crypto/ec_private_key_nss.cc[diff]
• crypto/ec_signature_creator_nss.cc[diff]
• crypto/third_party/nss/secsign.cc[diff]
• ipc/ipc_channel.h[diff]
• ipc/ipc_channel_posix.cc[diff]
• ipc/ipc_platform_file.cc[diff]
• net/base/x509_util_nss.cc[diff]
• ppapi/tests/test_broker.cc[diff]
• ui/gfx/skia_utils_gtk.cc[diff]
• webkit/glue/webkit_glue.gypi[diff]
• webkit/plugins/ppapi/ppb_flash_impl.cc[diff]
• webkit/plugins/ppapi/ppb_video_capture_impl.cc[diff]