Move the ProcessWatcher methods out of content/common/process_watcher into base/process_util, alongside the other process methods.

The only non-trivial move change is to the Windows implementation, where I changed KillProcess to use an exit code of kProcessKilledExitCode instead of content::RESULT_CODE_HUNG. cpu said that the existing code was incorrect, since GetTerminationStatus() should be mapping that result to TERMINATION_STATUS_PROCESS_WAS_KILLED. So I changed the exit code to kProcessKilledExitCode. This might make the UMA stats for killed processes to go up (and crashed to go down), but that will be an accounting change and should be zero-sum.

BUG=98716
Review URL: http://codereview.chromium.org/8674003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111371 0039d316-1c4b-4281-b951-d872f2087c98

diff --git a/base/process_util.h b/base/process_util.h
index 1143cd8..874e656 100644
--- a/base/process_util.h
+++ b/base/process_util.h

@@ -499,6 +499,28 @@
                                   int exit_code,
                                   const ProcessFilter* filter);
 
+// This method ensures that the specified process eventually terminates, and
+// then it closes the given process handle.
+//
+// It assumes that the process has already been signalled to exit, and it
+// begins by waiting a small amount of time for it to exit.  If the process
+// does not appear to have exited, then this function starts to become
+// aggressive about ensuring that the process terminates.
+//
+// On Linux this method does not block the calling thread.
+// On OS X this method may block for up to 2 seconds.
+//
+// NOTE: The process handle must have been opened with the PROCESS_TERMINATE
+// and SYNCHRONIZE permissions.
+//
+BASE_EXPORT void EnsureProcessTerminated(ProcessHandle process_handle);
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+// The nicer version of EnsureProcessTerminated() that is patient and will
+// wait for |process_handle| to finish and then reap it.
+BASE_EXPORT void EnsureProcessGetsReaped(ProcessHandle process_handle);
+#endif
+
 // This class provides a way to iterate through a list of processes on the
 // current machine with a specified filter.
 // To use, create an instance and then call NextProcessEntry() until it returns