Move fxcrt::{Byte,Wide}Strings with std::move().chromium/3466

Remove some string copies in barcode that were noticed whilst
looking for moves.

Change-Id: Ieda34d00f633576ba1f0dca283dcdabfb36f236c
Reviewed-on: https://pdfium-review.googlesource.com/35410
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

3 files changed, 19 insertions, 18 deletions

diff --git a/fpdfsdk/cpdfsdk_interform.cpp b/fpdfsdk/cpdfsdk_interform.cpp
index 1e247465c8..379a8b999d 100644
--- a/fpdfsdk/cpdfsdk_interform.cpp
+++ b/fpdfsdk/cpdfsdk_interform.cpp
@@ -10,6 +10,7 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "core/fpdfapi/page/cpdf_page.h"
@@ -322,13 +323,11 @@ WideString CPDFSDK_InterForm::OnFormat(CPDF_FormField* pFormField,
       WideString script = action.GetJavaScript();
       if (!script.IsEmpty()) {
         WideString Value = sValue;
-
         IJS_Runtime::ScopedEventContext pContext(pRuntime);
         pContext->OnField_Format(pFormField, Value, true);
-
         Optional<IJS_Runtime::JS_Error> err = pContext->RunScript(script);
         if (!err) {
-          sValue = Value;
+          sValue = std::move(Value);
           bFormatted = true;
         }
       }
diff --git a/fpdfsdk/fpdf_flatten.cpp b/fpdfsdk/fpdf_flatten.cpp
index 4b9e1f8a9d..b9e29be8b4 100644
--- a/fpdfsdk/fpdf_flatten.cpp
+++ b/fpdfsdk/fpdf_flatten.cpp
@@ -299,7 +299,7 @@ FPDF_EXPORT int FPDF_CALLCONV FPDFPage_Flatten(FPDF_PAGE page, int nFlag) {
     while (i < INT_MAX) {
       ByteString sKey = ByteString::Format("FFT%d", i);
       if (!pPageXObject->KeyExist(sKey)) {
-        key = sKey;
+        key = std::move(sKey);
         break;
       }
       ++i;
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
index faa2fa5e42..386ea95f5e 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
@@ -7,6 +7,7 @@
 #include "fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.h"
 
 #include <memory>
+#include <utility>
 
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
@@ -848,27 +849,28 @@ bool CPDFXFA_DocEnvironment::MailToInfo(WideString& csURL,
     return false;
 
   auto pos = srcURL.Find(L'?');
-  WideString tmp;
-  if (!pos.has_value()) {
-    pos = srcURL.Find(L'@');
-    if (!pos.has_value())
-      return false;
 
-    tmp = srcURL.Right(csURL.GetLength() - 7);
-  } else {
-    tmp = srcURL.Left(pos.value());
-    tmp = tmp.Right(tmp.GetLength() - 7);
-  }
-  tmp.Trim();
+  {
+    WideString tmp;
+    if (!pos.has_value()) {
+      pos = srcURL.Find(L'@');
+      if (!pos.has_value())
+        return false;
 
-  csToAddress = tmp;
+      tmp = srcURL.Right(csURL.GetLength() - 7);
+    } else {
+      tmp = srcURL.Left(pos.value());
+      tmp = tmp.Right(tmp.GetLength() - 7);
+    }
+    tmp.Trim();
+    csToAddress = std::move(tmp);
+  }
 
   srcURL = srcURL.Right(srcURL.GetLength() - (pos.value() + 1));
   while (!srcURL.IsEmpty()) {
     srcURL.Trim();
     pos = srcURL.Find(L'&');
-
-    tmp = (!pos.has_value()) ? srcURL : srcURL.Left(pos.value());
+    WideString tmp = (!pos.has_value()) ? srcURL : srcURL.Left(pos.value());
     tmp.Trim();
     if (tmp.GetLength() >= 3 && tmp.Left(3).CompareNoCase(L"cc=") == 0) {
       tmp = tmp.Right(tmp.GetLength() - 3);