Roll forward to cl/338482889

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I9850950db8bd84f0904ea1a413151887f52098cf

cpp/platform/api/log_message.h

@@ -0,0 +1,41 @@
+#ifndef PLATFORM_API_LOG_MESSAGE_H_
+#define PLATFORM_API_LOG_MESSAGE_H_
+
+#include <iostream>
+
+namespace location {
+namespace nearby {
+namespace api {
+
+// A log message that prints to appropraite destination when ~LogMessage() is
+// called.
+class LogMessage {
+ public:
+  enum class Severity {
+    kInfo = 0,
+    kWarning = 1,
+    kError = 2,
+    kFatal = 3,  // Terminates the process after logging
+  };
+
+  // Configures minimum severity to be logged.
+  static void SetMinLogSeverity(Severity severity);
+
+  // Returns if a log with |severity| should be logged based on
+  // SetMinLogSeverity and additional platform requirements.
+  static bool ShouldCreateLogMessage(Severity severity);
+
+  virtual ~LogMessage() = default;
+
+  // Printf like logging.
+  virtual void Print(const char* format, ...) = 0;
+
+  // Returns a stream for std::cout like logging.
+  virtual std::ostream& Stream() = 0;
+};
+
+}  // namespace api
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API_LOG_MESSAGE_H_