Remove some usage of |return XXX.release()| anti-pattern.

core/fpdfapi/page/cpdf_image.h

Index: core/fpdfapi/page/cpdf_image.h
diff --git a/core/fpdfapi/page/cpdf_image.h b/core/fpdfapi/page/cpdf_image.h
index e0fc761b385ab389d6d3d9beaaa23f6c3924ff77..6591897d1e2f675fdefc2e5dd440f3ccc57b11fe 100644
--- a/core/fpdfapi/page/cpdf_image.h
+++ b/core/fpdfapi/page/cpdf_image.h
@@ -44,11 +44,11 @@ class CPDF_Image {
   bool IsMask() const { return m_bIsMask; }
   bool IsInterpol() const { return m_bInterpolate; }
 
-  CFX_DIBSource* LoadDIBSource(CFX_DIBSource** ppMask = nullptr,
-                               uint32_t* pMatteColor = nullptr,
-                               bool bStdCS = false,
-                               uint32_t GroupFamily = 0,
-                               bool bLoadMask = false) const;
+  std::unique_ptr<CFX_DIBSource> LoadDIBSource(CFX_DIBSource** ppMask = nullptr,
+                                               uint32_t* pMatteColor = nullptr,
+                                               bool bStdCS = false,
+                                               uint32_t GroupFamily = 0,
+                                               bool bLoadMask = false) const;
 
   void SetImage(const CFX_DIBitmap* pDIBitmap);
   void SetJpegImage(const CFX_RetainPtr<IFX_SeekableReadStream>& pFile);