Remove three unused variables, no bug

netwerk/protocol/http/nsHttpChannel.cpp

@@ -58,11 +58,6 @@ namespace mozilla { namespace net {
 
 namespace {
 
-// Device IDs for various cache types
-const char kDiskDeviceID[] = "disk";
-const char kMemoryDeviceID[] = "memory";
-const char kOfflineDeviceID[] = "offline";
-
 // True if the local cache should be bypassed when processing a request.
 #define BYPASS_LOCAL_CACHE(loadFlags) \
         (loadFlags & (nsIRequest::LOAD_BYPASS_CACHE | \