cros_generate_breakpad_symbols: Change GenerateBreakpadSymbol return.

Make GenerateBreakpadSymbol return the symbol file it's writing
out. This has no effect outside of unittests, but is needed for Ryu
symbol processing in another repository.

BUG=b/21954100
TEST=Unittests + manual testing with ryu scripts.

Change-Id: Ia30177613ff7fbb1b9ba573e564856a887b41f44
Reviewed-on: https://chromium-review.googlesource.com/303496
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Matthew Sartori <msartori@chromium.org>
diff --git a/scripts/cros_generate_breakpad_symbols.py b/scripts/cros_generate_breakpad_symbols.py
index 78c1541..92a242e 100644
--- a/scripts/cros_generate_breakpad_symbols.py
+++ b/scripts/cros_generate_breakpad_symbols.py
@@ -76,7 +76,7 @@
     dump_syms_cmd: Command to use for dumping symbols.
 
   Returns:
-    The number of errors that were encountered.
+    The name of symbol file written out.
   """
   assert breakpad_dir
   if num_errors is None:
@@ -151,7 +151,7 @@
     os.chmod(sym_file, 0o644)
     temp.delete = False
 
-  return num_errors.value
+  return sym_file
 
 
 def GenerateBreakpadSymbols(board, breakpad_dir=None, strip_cfi=False,