This adds some plumbing for propagating the status and error code of a...

This adds some plumbing for propagating the status and error code of a renderer process that went away so that we can tell at the UI level what happened to the tab: did it crash, or was it killed by the OOM killer (or some other reason). This is in preparation for implementing a new UI for when a process is killed by the OOM on ChromeOS which handles it differently from a crash.

Most of the changes are modifications of the argument list to include a status and error code for the exited process, but in addition the following was done:

- Changed the name of DidProcessCrash to GetTerminationStatus.
- Added TerminationStatus enum in process_util.h, so it can be used as the status returned by GetTerminationStatus.
- Improved process_util_unittest to actually test for crashing and terminated processes on all platforms.
- Added a new notification for renderers that were killed.
- Added error code information to crash notification.
- Added status and error code information to renderer IPC message for RenderViewGone.
- Added a UMA histogram count for number of renderer kills.

BUG=http://crosbug.com/8505
TEST=ran new unit test. Test passes on try servers.

Review URL: http://codereview.chromium.org/5172009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69082 0039d316-1c4b-4281-b951-d872f2087c98