[login_manager] throw the switch to in-chrome authentication

This CL begins obsoleting pam_google.  Instead of execing a setuid helper binary
from within chrome that loads pam_google to do authentication, chrome
talks to ClientLogin itself, and then does some other HTTP requests to fetch the
user's google accounts cookies.

BUG=314

TEST=ensure you've got this patch; try logging in.  Also, ran desktopui_DoLogin, login_CryptohomeMounted, login_CryptohomeUnmounted, etc.

Review URL: http://codereview.chromium.org/1640006
diff --git a/session_manager_setup.sh b/session_manager_setup.sh
index ce9a4fb..a99829c 100755
--- a/session_manager_setup.sh
+++ b/session_manager_setup.sh
@@ -89,7 +89,6 @@
 
 CHROME_DIR="/opt/google/chrome"
 CHROME="$CHROME_DIR/chrome"
-COOKIE_PIPE="/tmp/cookie_pipe"
 SEND_METRICS="/etc/send_metrics"
 CONSENT_FILE="$DATA_DIR/Consent To Send Stats"
 
@@ -145,6 +144,6 @@
             --no-first-run \
             --user-data-dir=/home/$USER \
             --login-profile=user \
-            "--cookie-pipe=$COOKIE_PIPE" \
+            --in-chrome-auth \
             --enable-login-images \
             "${SKIP_OOBE}"