Add has_value() and value() methods to rtc::Optional.

webrtc/base/optional.h

Index: webrtc/base/optional.h
diff --git a/webrtc/base/optional.h b/webrtc/base/optional.h
index c8ed069d55570b1f6bf5e7191bcf121626dd0a0b..4f883a886295fad3867d5293bf60f788dc2366b4 100644
--- a/webrtc/base/optional.h
+++ b/webrtc/base/optional.h
@@ -218,6 +218,7 @@ class Optional final {
 
   // Conversion to bool to test if we have a value.
   explicit operator bool() const { return has_value_; }
+  bool has_value() const { return has_value_; }
 
   // Dereferencing. Only allowed if we have a value.
   const T* operator->() const {
@@ -236,6 +237,14 @@ class Optional final {
     RTC_DCHECK(has_value_);
     return value_;
   }
+  const T& value() const {
+    RTC_DCHECK(has_value_);
+    return value_;
+  }
+  T& value() {
+    RTC_DCHECK(has_value_);
+    return value_;
+  }
 
   // Dereference with a default value in case we don't have a value.
   const T& value_or(const T& default_val) const {