Collect unclean shutdown debug information

base/debug/activity_analyzer.cc

Index: base/debug/activity_analyzer.cc
diff --git a/base/debug/activity_analyzer.cc b/base/debug/activity_analyzer.cc
index 54e566b31a98169bc42b0392f49a90d2411e1f1a..0bbcfe2298ecfc9831d6ce85d1b6e000d0533ab2 100644
--- a/base/debug/activity_analyzer.cc
+++ b/base/debug/activity_analyzer.cc
@@ -4,6 +4,8 @@
 
 #include "base/debug/activity_analyzer.h"
 
+#include <utility>
+
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
@@ -42,7 +44,9 @@ GlobalActivityAnalyzer::~GlobalActivityAnalyzer() {}
 std::unique_ptr<GlobalActivityAnalyzer> GlobalActivityAnalyzer::CreateWithFile(
     const FilePath& file_path) {
   std::unique_ptr<MemoryMappedFile> mmfile(new MemoryMappedFile());
-  mmfile->Initialize(file_path);
+  // Note: write access is required for snapshotting, which writes a sentinel to
+  // ensure the snapshot's consistency.
+  mmfile->Initialize(file_path, MemoryMappedFile::READ_WRITE);
   if (!mmfile->IsValid())
     return nullptr;