Exit cleanly when sending kZygoteMagic failed.

ChromeOS may kill chrome right after process
starts (when a user closes lid right away for example), and
sending magic number to browser process can fail. Instead of
CHECK, exit normally on chromeos.

BUG=chromium-os:17606
TEST=autotest will not crash with session manager sending SIGTERM

Review URL: http://codereview.chromium.org/7433011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@93171 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/zygote_main_linux.cc

@@ -123,7 +123,15 @@ class Zygote {
       std::vector<int> empty;
       bool r = UnixDomainSocket::SendMsg(kBrowserDescriptor, kZygoteMagic,
                                          sizeof(kZygoteMagic), empty);
+#if defined(OS_CHROMEOS)
+      LOG_IF(WARNING, r) << "Sending zygote magic failed";
+      // Exit normally on chromeos because session manager may send SIGTERM
+      // right after the process starts and it may fail to send zygote magic
+      // number to browser process.
+      _exit(content::RESULT_CODE_NORMAL_EXIT);
+#else
       CHECK(r) << "Sending zygote magic failed";
+#endif
     }
 
     for (;;) {