 Updating BreakpadController to allow start and stop being nop.
 Updating BreakpadController to allow start and stop being nop.

 When BreakpadController is already started or stopped, trying to restart it or
restopping it will now be no-op instead of asserting.
Review URL: https://breakpad.appspot.com/505002

git-svn-id: a14e546401035be51a469fbea25ecce70a1a22f2@1092 4c0a9323-5329-0410-9bdc-e9ce6186880e

tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad