Add base::debug::ScopedCrashKeyString.

This is the new version of base::debug::ScopedCrashKey.

Bug: 598854
Change-Id: Idfea07f414c4c68fb51909de467c8e666acd841d
Reviewed-on: https://chromium-review.googlesource.com/811287
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522145}

base/debug/crash_logging.cc

@@ -73,6 +73,16 @@ void ClearCrashKeyString(CrashKeyString* crash_key) {
   g_crash_key_impl->Clear(crash_key);
 }
 
+ScopedCrashKeyString::ScopedCrashKeyString(CrashKeyString* crash_key,
+                                           base::StringPiece value)
+    : crash_key_(crash_key) {
+  SetCrashKeyString(crash_key_, value);
+}
+
+ScopedCrashKeyString::~ScopedCrashKeyString() {
+  ClearCrashKeyString(crash_key_);
+}
+
 void SetCrashKeyImplementation(std::unique_ptr<CrashKeyImplementation> impl) {
   delete g_crash_key_impl;
   g_crash_key_impl = impl.release();

base/debug/crash_logging.h

@@ -59,6 +59,19 @@ BASE_EXPORT void SetCrashKeyString(CrashKeyString* crash_key,
 // null.
 BASE_EXPORT void ClearCrashKeyString(CrashKeyString* crash_key);
 
+// A scoper that sets the specified key to value for the lifetime of the
+// object, and clears it on destruction.
+class BASE_EXPORT ScopedCrashKeyString {
+ public:
+  ScopedCrashKeyString(CrashKeyString* crash_key, base::StringPiece value);
+  ~ScopedCrashKeyString();
+
+ private:
+  CrashKeyString* const crash_key_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedCrashKeyString);
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 // The following declarations are used to initialize the crash key system
 // in //base by providing implementations for the above functions.