crash-reporter: Add diagnostics to help diagnose failures in the wild

system_logging.h

Index: system_logging.h
diff --git a/system_logging.h b/system_logging.h
index 7ebfc5e5934c3f6e90910a15cd88b11e9399be7f..d1f72a56e6f51d06f62ed4ab70e8b7b32d0380c4 100644
--- a/system_logging.h
+++ b/system_logging.h
@@ -5,6 +5,7 @@
 #ifndef CRASH_REPORTER_SYSTEM_LOGGING_H_
 #define CRASH_REPORTER_SYSTEM_LOGGING_H_
 
+#include <stdarg.h>
 #include <string>
 
 class SystemLogging {
@@ -13,8 +14,12 @@ class SystemLogging {
   virtual void LogInfo(const char *format, ...) = 0;
   virtual void LogWarning(const char *format, ...) = 0;
   virtual void LogError(const char *format, ...) = 0;
+  virtual void set_accumulating(bool value) = 0;
+  virtual std::string get_accumulator() = 0;
 };
 
+// SystemLoggingImpl implements SystemLogging but adds the
+// capability of accumulating the log to a STL string.
 class SystemLoggingImpl : public SystemLogging {
  public:
   SystemLoggingImpl();
@@ -23,8 +28,18 @@ class SystemLoggingImpl : public SystemLogging {
   virtual void LogInfo(const char *format, ...);
   virtual void LogWarning(const char *format, ...);
   virtual void LogError(const char *format, ...);
+  virtual void set_accumulating(bool value) {
+    is_accumulating_ = value;
+  }
+  virtual std::string get_accumulator() {
+    return accumulator_;
+  }
  private:
   static std::string identity_;
+  std::string accumulator_;
+  bool is_accumulating_;
+  void LogWithLevel(int level, const char *format,
+                    va_list arg_list);
 };
 
 #endif  // CRASH_REPORTER_SYSTEM_LOGGING_H_