Move MinPositive to call.h

webrtc/call/call.h

Index: webrtc/call/call.h
diff --git a/webrtc/call/call.h b/webrtc/call/call.h
index 06479890ce151c4d8b667d489aaf7dff2f87e0be..5aa0836fa19ca011563ee0141f2af6d91d92cf0f 100644
--- a/webrtc/call/call.h
+++ b/webrtc/call/call.h
@@ -10,6 +10,7 @@
 #ifndef WEBRTC_CALL_CALL_H_
 #define WEBRTC_CALL_CALL_H_
 
+#include <algorithm>
 #include <memory>
 #include <string>
 #include <vector>
@@ -39,6 +40,19 @@ enum class MediaType {
   DATA
 };
 
+// Like std::min, but considers non-positive values to be unset.
+// TODO(zstein): Remove once all callers use rtc::Optional.
+template <typename T>
+static T MinPositive(T a, T b) {
+  if (a <= 0) {
+    return b;
+  }
+  if (b <= 0) {
+    return a;
+  }
+  return std::min(a, b);
+}
+
 class PacketReceiver {
  public:
   enum DeliveryStatus {