Add unit_tests (Chrome browser unit tests) to Mac/Linux coverage.
Minor fixes to coverage related scripts.

Review URL: http://codereview.chromium.org/118298

git-svn-id: http://src.chromium.org/svn/trunk/src/third_party/lcov@17785 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/bin/mcov b/bin/mcov
index b04324b..8bbb2cc 100755
--- a/bin/mcov
+++ b/bin/mcov
@@ -252,8 +252,10 @@
   my $number;
   local *INPUT;
 
-  ## TODO(ajeya): Exit more gracefully here.
-  open(INPUT, $filename) or die("ERROR: cannot read $filename!\n");
+  if (!open(INPUT, $filename)) {
+    warn("WARNING: cannot read $filename!\n");
+    return @result;
+  }
   
   # Parse gcov output and populate the array
   my @lines = <INPUT>;