Avoid const-refs to implicitly constructed strings.

Because the invisible temporary goes out of scope at the next
semicolon.

Also avoid returning const string references since the cost is
low to properly keep the string alive.

Change-Id: Id283e4fd99f79a02d79d739a533a4ce05e831e2a
Reviewed-on: https://pdfium-review.googlesource.com/35710
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

3 files changed, 3 insertions, 5 deletions

diff --git a/core/fpdfapi/parser/cpdf_object_walker.cpp b/core/fpdfapi/parser/cpdf_object_walker.cpp
index cb59a05d06..3aaa25e9f7 100644
--- a/core/fpdfapi/parser/cpdf_object_walker.cpp
+++ b/core/fpdfapi/parser/cpdf_object_walker.cpp
@@ -57,7 +57,7 @@ class DictionaryIterator : public CPDF_ObjectWalker::SubobjectIterator {
     dict_iterator_ = object()->GetDict()->begin();
   }
 
-  const ByteString& dict_key() const { return dict_key_; }
+  ByteString dict_key() const { return dict_key_; }
 
  private:
   CPDF_Dictionary::const_iterator dict_iterator_;
diff --git a/core/fpdfapi/parser/cpdf_object_walker.h b/core/fpdfapi/parser/cpdf_object_walker.h
index 8cad3c32f3..d677712c9b 100644
--- a/core/fpdfapi/parser/cpdf_object_walker.h
+++ b/core/fpdfapi/parser/cpdf_object_walker.h
@@ -41,7 +41,7 @@ class CPDF_ObjectWalker {
 
   size_t current_depth() const { return current_depth_; }
   const CPDF_Object* GetParent() const { return parent_object_; }
-  const ByteString& dictionary_key() const { return dict_key_; }
+  ByteString dictionary_key() const { return dict_key_; }
 
  private:
   static std::unique_ptr<SubobjectIterator> MakeIterator(
@@ -49,10 +49,8 @@ class CPDF_ObjectWalker {
 
   const CPDF_Object* next_object_;
   const CPDF_Object* parent_object_;
-
   ByteString dict_key_;
   size_t current_depth_;
-
   std::stack<std::unique_ptr<SubobjectIterator>> stack_;
 };
 
diff --git a/core/fpdfapi/parser/cpdf_stream_acc.h b/core/fpdfapi/parser/cpdf_stream_acc.h
index cd836340fd..00bd353fcb 100644
--- a/core/fpdfapi/parser/cpdf_stream_acc.h
+++ b/core/fpdfapi/parser/cpdf_stream_acc.h
@@ -36,7 +36,7 @@ class CPDF_StreamAcc : public Retainable {
   pdfium::span<uint8_t> GetSpan() const {
     return pdfium::make_span(GetData(), GetSize());
   }
-  const ByteString& GetImageDecoder() const { return m_ImageDecoder; }
+  ByteString GetImageDecoder() const { return m_ImageDecoder; }
   const CPDF_Dictionary* GetImageParam() const { return m_pImageParam; }
   std::unique_ptr<uint8_t, FxFreeDeleter> DetachData();