Allow generating minidumps from live process on Linux via ExceptionHandler

Original patch by Chris Jones <jones.chris.g@gmail.com> at https://bugzilla.mozilla.org/show_bug.cgi?id=544936 and https://bugzilla.mozilla.org/show_bug.cgi?id=555309
R=mark at https://breakpad.appspot.com/449003/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1043 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/client/linux/handler/exception_handler.h

@@ -167,6 +167,23 @@ class ExceptionHandler {
                             MinidumpCallback callback,
                             void* callback_context);
 
+  // Write a minidump of |child| immediately.  This can be used to
+  // capture the execution state of |child| independently of a crash.
+  // Pass a meaningful |child_blamed_thread| to make that thread in
+  // the child process the one from which a crash signature is
+  // extracted.
+  //
+  // WARNING: the return of this function *must* happen before
+  // the code that will eventually reap |child| executes.
+  // Otherwise there's a pernicious race condition in which |child|
+  // exits, is reaped, another process created with its pid, then that
+  // new process dumped.
+  static bool WriteMinidumpForChild(pid_t child,
+                                    pid_t child_blamed_thread,
+                                    const string& dump_path,
+                                    MinidumpCallback callback,
+                                    void* callback_context);
+
   // This structure is passed to minidump_writer.h:WriteMinidump via an opaque
   // blob. It shouldn't be needed in any user code.
   struct CrashContext {