split ui/base/clipboard constants out for split_link

ui/base/clipboard/clipboard.cc

Index: ui/base/clipboard/clipboard.cc
diff --git a/ui/base/clipboard/clipboard.cc b/ui/base/clipboard/clipboard.cc
index 168b59845f44cdc81465c9054cba6171ff1e95e8..684d8d5293632e9fcafbcdd3856698e966419bff 100644
--- a/ui/base/clipboard/clipboard.cc
+++ b/ui/base/clipboard/clipboard.cc
@@ -103,13 +103,6 @@ union SourceTag2BinaryHelper {
 
 }  // namespace
 
-const char Clipboard::kMimeTypeText[] = "text/plain";
-const char Clipboard::kMimeTypeURIList[] = "text/uri-list";
-const char Clipboard::kMimeTypeDownloadURL[] = "downloadurl";
-const char Clipboard::kMimeTypeHTML[] = "text/html";
-const char Clipboard::kMimeTypeRTF[] = "text/rtf";
-const char Clipboard::kMimeTypePNG[] = "image/png";
-
 // static
 Clipboard::ObjectMapParam Clipboard::SourceTag2Binary(SourceTag tag) {
   SourceTag2BinaryHelper helper;