crash_sender: fix orphan logic, prevent deletion of *.log.tar.xz

get_base() was broken for files with multiple extensions which leads the orphan
logic to delete all such files that are older than 1 day.  This patch set fixes
get_base().

BUG=chromium:338977
TEST=manual test of code fragment
TEST=`cbuildbot {arm,amd64,x86}-generic-full` pass
CQ-DEPEND=CL:199820

Change-Id: I1b712f1a5cfc848e5bc2a86c97e0a3e88ce6250d
Reviewed-on: https://chromium-review.googlesource.com/199511
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/crash_reporter/crash_collector.cc b/crash_reporter/crash_collector.cc
index 89d9304..5ddff08 100644
--- a/crash_reporter/crash_collector.cc
+++ b/crash_reporter/crash_collector.cc
@@ -108,6 +108,8 @@
 }
 
 std::string CrashCollector::Sanitize(const std::string &name) {
+  // Make sure the sanitized name does not include any periods.
+  // The logic in crash_sender relies on this.
   std::string result = name;
   for (size_t i = 0; i < name.size(); ++i) {
     if (!isalnum(result[i]) && result[i] != '_')