media: Use stl utilities from the base namespace

media/blink/cdm_session_adapter.cc

Index: media/blink/cdm_session_adapter.cc
diff --git a/media/blink/cdm_session_adapter.cc b/media/blink/cdm_session_adapter.cc
index 4558bbe27b1c6e2cbc83d8d26180e096ccf2c771..49694a9d2d61edec3ef69646e65b08d8de1e1fd5 100644
--- a/media/blink/cdm_session_adapter.cc
+++ b/media/blink/cdm_session_adapter.cc
@@ -77,7 +77,7 @@ bool CdmSessionAdapter::RegisterSession(
     const std::string& session_id,
     base::WeakPtr<WebContentDecryptionModuleSessionImpl> session) {
   // If this session ID is already registered, don't register it again.
-  if (ContainsKey(sessions_, session_id))
+  if (base::ContainsKey(sessions_, session_id))
     return false;
 
   sessions_[session_id] = session;
@@ -85,7 +85,7 @@ bool CdmSessionAdapter::RegisterSession(
 }
 
 void CdmSessionAdapter::UnregisterSession(const std::string& session_id) {
-  DCHECK(ContainsKey(sessions_, session_id));
+  DCHECK(base::ContainsKey(sessions_, session_id));
   sessions_.erase(session_id);
 }