Allow getting an uncached process map.

Change-Id: I58d7e90a7b5c4476a4b9f51640c54d13748ac220
diff --git a/include/backtrace/BacktraceMap.h b/include/backtrace/BacktraceMap.h
index c717f09..4ed23a8 100644
--- a/include/backtrace/BacktraceMap.h
+++ b/include/backtrace/BacktraceMap.h
@@ -41,7 +41,10 @@
 
 class BacktraceMap {
 public:
-  static BacktraceMap* Create(pid_t pid);
+  // If uncached is true, then parse the current process map as of the call.
+  // Passing a map created with uncached set to true to Backtrace::Create()
+  // is unsupported.
+  static BacktraceMap* Create(pid_t pid, bool uncached = false);
 
   virtual ~BacktraceMap();