Add more tests for H264 profile level id parsing

webrtc/common_video/h264/profile_level_id.cc

Index: webrtc/common_video/h264/profile_level_id.cc
diff --git a/webrtc/common_video/h264/profile_level_id.cc b/webrtc/common_video/h264/profile_level_id.cc
index 6d8c5c0ce80fa18819759ae4da190da9b79738af..c7b7f2c2fffd13f8796fe92fd0999ee422dba68d 100644
--- a/webrtc/common_video/h264/profile_level_id.cc
+++ b/webrtc/common_video/h264/profile_level_id.cc
@@ -139,7 +139,7 @@ rtc::Optional<std::string> ProfileLevelIdToString(
       case kProfileBaseline:
         return rtc::Optional<std::string>("42100b");
       case kProfileMain:
-        return rtc::Optional<std::string>("4D100b");
+        return rtc::Optional<std::string>("4d100b");
       // Level 1b is not allowed for other profiles.
       default:
         return rtc::Optional<std::string>();
@@ -155,7 +155,7 @@ rtc::Optional<std::string> ProfileLevelIdToString(
       profile_idc_iop_string = "4200";
       break;
     case kProfileMain:
-      profile_idc_iop_string = "4D00";
+      profile_idc_iop_string = "4d00";
       break;
     case kProfileConstrainedHigh:
       profile_idc_iop_string = "640c";