Suppress a memory leak in the gtk omnibox

tools/valgrind/memcheck/suppressions.txt

 # There are three kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 3165 matching lines @@
    fun:_ZN7testing35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS3_FS2_vEPKc
 }
 {
    bug_61424_b
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN13FormStructure18EncodeQueryRequestERK12ScopedVectorIS_EPSt6vectorISsSaISsEEPSs
    fun:_ZN12_GLOBAL__N_141FormStructureTest_EncodeQueryRequest_Test8TestBodyEv
    fun:_ZN7testingL35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS3_FS2_vEPKc
 }
+{
+   bug_61685
+   Memcheck:Leak
+   fun:malloc
+   ...
+   fun:gtk_text_buffer_select_range
+   fun:_ZN23AutocompleteEditViewGtk16SetSelectedRangeERKNS_9CharRangeE
+   fun:_ZN23AutocompleteEditViewGtk23SetTextAndSelectedRangeERKSbIwSt11char_traitsIwESaIwEERKNS_9CharRangeE
+   fun:_ZN23AutocompleteEditViewGtk24SetWindowTextAndCaretPosERKSbIwSt11char_traitsIwESaIwEEj
+   fun:_ZN21AutocompleteEditModel6RevertEv
+   fun:_ZN23AutocompleteEditViewGtk9RevertAllEv
+   fun:_ZN23AutocompleteEditViewGtk6UpdateEPK11TabContents
+   fun:_ZN15LocationBarView6UpdateEPK11TabContents
+}