EME: Remove reference to "concrete" key systems.

media/base/key_systems_unittest.cc

Index: media/base/key_systems_unittest.cc
diff --git a/media/base/key_systems_unittest.cc b/media/base/key_systems_unittest.cc
index 0eee5fed8c4fa5121d9f9537e55f1b6ef4a185b6..9d33c0691c5552dcaa05b4f0d6c5dc660077a819 100644
--- a/media/base/key_systems_unittest.cc
+++ b/media/base/key_systems_unittest.cc
@@ -388,9 +388,8 @@ TEST_F(KeySystemsTest, Basic_UnrecognizedKeySystem) {
 
 #if defined(ENABLE_PEPPER_CDMS)
   std::string type;
-  EXPECT_DEBUG_DEATH(
-      type = GetPepperType(kUnrecognized),
-      "x-org.example.unrecognized is not a known concrete system");
+  EXPECT_DEBUG_DEATH(type = GetPepperType(kUnrecognized),
+                     "x-org.example.unrecognized is not a known system");
   EXPECT_TRUE(type.empty());
 #endif
 }