Don't attempt to forward declare StringPiece.

1) This is discouraged because it prevents callers from benefiting from automatic coersion from string/char* types.
2) A follow-up CL (http://codereview.chromium.org/8659047/) will make StringPiece a template, and thus awkward to forward declare. The very small number of places that were appropriately forward declaring it do not justify writing a 'string_piece_forward.h'.

BUG=87634
R=sky@chromium.org


Review URL: http://codereview.chromium.org/8815013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113423 0039d316-1c4b-4281-b951-d872f2087c98

ui/base/resource/data_pack.h

@@ -14,15 +14,12 @@
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/string_piece.h"
 #include "ui/base/ui_export.h"
 
 class FilePath;
 class RefCountedStaticMemory;
 
-namespace base {
-class StringPiece;
-}
-
 namespace file_util {
 class MemoryMappedFile;
 }

ui/base/resource/resource_bundle.h

@@ -22,6 +22,7 @@
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
+#include "base/string_piece.h"
 #include "ui/base/ui_export.h"
 #include "ui/gfx/native_widget_types.h"
 
@@ -30,7 +31,6 @@ typedef uint32 SkColor;
 
 namespace base {
 class Lock;
-class StringPiece;
 }
 
 namespace gfx {