Move StringPiece to libandroidfw

libandroidfw needs to make use of StringPiece, so
move it to libandroidfw and update all code referencing
StringPiece in aapt2.

Test: make libandroidfw_tests libaapt2_tests
Change-Id: I68d7f0fc7c651b048d9d1f5e7971f10ef5349fa1
diff --git a/tools/aapt2/compile/Pseudolocalizer.h b/tools/aapt2/compile/Pseudolocalizer.h
index a6d2ad0..6cf003b 100644
--- a/tools/aapt2/compile/Pseudolocalizer.h
+++ b/tools/aapt2/compile/Pseudolocalizer.h
@@ -20,10 +20,10 @@
 #include <memory>
 
 #include "android-base/macros.h"
+#include "androidfw/StringPiece.h"
 
 #include "ResourceValues.h"
 #include "StringPool.h"
-#include "util/StringPiece.h"
 
 namespace aapt {
 
@@ -32,8 +32,8 @@
   virtual ~PseudoMethodImpl() {}
   virtual std::string Start() { return {}; }
   virtual std::string End() { return {}; }
-  virtual std::string Text(const StringPiece& text) = 0;
-  virtual std::string Placeholder(const StringPiece& text) = 0;
+  virtual std::string Text(const android::StringPiece& text) = 0;
+  virtual std::string Placeholder(const android::StringPiece& text) = 0;
 };
 
 class Pseudolocalizer {
@@ -48,7 +48,7 @@
   void SetMethod(Method method);
   std::string Start() { return impl_->Start(); }
   std::string End() { return impl_->End(); }
-  std::string Text(const StringPiece& text);
+  std::string Text(const android::StringPiece& text);
 
  private:
   std::unique_ptr<PseudoMethodImpl> impl_;