Add support for logging absl::string_view.

Bug: webrtc:8982
Change-Id: I5691f91ea663756666cf187ee223ede50f87d5f0
Reviewed-on: https://webrtc-review.googlesource.com/99840
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24707}
diff --git a/rtc_base/logging.h b/rtc_base/logging.h
index 1a14c33..4f74dcf 100644
--- a/rtc_base/logging.h
+++ b/rtc_base/logging.h
@@ -55,6 +55,7 @@
 #include <CoreServices/CoreServices.h>
 #endif
 
+#include "absl/strings/string_view.h"
 #include "rtc_base/constructormagic.h"
 #include "rtc_base/deprecation.h"
 #include "rtc_base/strings/string_builder.h"
@@ -174,7 +175,7 @@
   kLongDouble,
   kCharP,
   kStdString,
-  // TODO(kwiberg): Add absl::StringView.
+  kStringView,
   kVoidP,
   kLogMetadata,
   kLogMetadataErr,
@@ -236,7 +237,10 @@
     const std::string& x) {
   return {&x};
 }
-// TODO(kwiberg): Add absl::string_view
+inline Val<LogArgType::kStringView, const absl::string_view*> MakeVal(
+    const absl::string_view& x) {
+  return {&x};
+}
 
 inline Val<LogArgType::kVoidP, const void*> MakeVal(const void* x) {
   return {x};