use std::string for skip messages (#1571)

include/benchmark/benchmark.h

diff --git a/include/benchmark/benchmark.h b/include/benchmark/benchmark.h
index bb29c73..783fcd8 100644
--- a/include/benchmark/benchmark.h
+++ b/include/benchmark/benchmark.h
@@ -760,7 +760,7 @@
   // the current scope immediately. If the function is called from within
   // the 'KeepRunning()' loop the current iteration will finish. It is the users
   // responsibility to exit the scope as needed.
-  void SkipWithMessage(const char* msg);
+  void SkipWithMessage(const std::string& msg);
 
   // REQUIRES: 'SkipWithMessage(...)' or 'SkipWithError(...)' has not been
   //            called previously by the current thread.
@@ -781,7 +781,7 @@
   // the current scope immediately. If the function is called from within
   // the 'KeepRunning()' loop the current iteration will finish. It is the users
   // responsibility to exit the scope as needed.
-  void SkipWithError(const char* msg);
+  void SkipWithError(const std::string& msg);
 
   // Returns true if 'SkipWithMessage(...)' or 'SkipWithError(...)' was called.
   bool skipped() const { return internal::NotSkipped != skipped_; }

src/benchmark.cc

diff --git a/src/benchmark.cc b/src/benchmark.cc
index f06f368..1937eea 100644
--- a/src/benchmark.cc
+++ b/src/benchmark.cc
@@ -236,8 +236,7 @@
   }
 }
 
-void State::SkipWithMessage(const char* msg) {
-  BM_CHECK(msg);
+void State::SkipWithMessage(const std::string& msg) {
   skipped_ = internal::SkippedWithMessage;
   {
     MutexLock l(manager_->GetBenchmarkMutex());
@@ -250,8 +249,7 @@
   if (timer_->running()) timer_->StopTimer();
 }
 
-void State::SkipWithError(const char* msg) {
-  BM_CHECK(msg);
+void State::SkipWithError(const std::string& msg) {
   skipped_ = internal::SkippedWithError;
   {
     MutexLock l(manager_->GetBenchmarkMutex());