Ignore a few more string functions to suppress reports on *_empty_rep_storage...

tools/valgrind/tsan/ignores.txt

 # This file lists the functions, object files and source files
 # which should be ignored (i.e. not instrumented) by ThreadSanitizer.
 
 # ignore these libraries
 obj:*/ld-2*
 obj:*/libpthread-*
 obj:*/libfreetype*
 
 # we ignore the whole NSS library for now since
 # its instrumentation is very slow.
@@ skipping 17 matching lines @@
 # dark magic with 'errno' here.
 fun:sys_*
 
 # ignore libc's printf functions
 fun:_IO_*
 fun:vfprintf
 fun:fwrite
 fun:fflush
 
 # 32-bit version of std::string
-# There is something very strange inside this function.
+# There is something very strange inside these functions.
 # Looks like they write zero to a global variable which
 # value is already zero. I.e. the race is benign.
 # Global var is _ZNSs4_Rep20_S_empty_rep_storageE
 fun:*_M_mutateE*
-# A similar report on another std::string member.
 fun:*_M_set_length_and_sharable*
+fun:*_M_is_leaked*
+fun:*_M_is_shared*
+fun:*_M_set_leaked*
+fun:*_M_set_sharable*
 
 # Don't instrument intercepts
 src:*ts_valgrind_intercepts.c
 
 ##################################################################
 # Don't instrument syncronization code
 src:*base/waitable_event*
 src:*base/atomic*
 src:*base/condition_variable*
 src:*base/lock*
@@ skipping 11 matching lines @@
 fun:*v8*internal*
 
 # TODO(timurrrr): SKIA - needs separate testing?
 # SKIA unittest is single-threaded...
 # SKIA uses un-annotated atomic refcount and other sync stuff
 # some functions are HEAVY like png, jpeg decoding
 src:*third_party/skia*
 
 # WebKit hotspot
 fun:*png_write*