fix a few linux compilation warnings

core/src/fpdfapi/fpdf_edit/fpdf_edit_image.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fxcodec/fx_codec.h"
 #include "../../../include/fpdfapi/fpdf_render.h"
@@ skipping 177 matching lines @@
     } else {
         pDict->SetAtName(FX_BSTRC("ColorSpace"), FX_BSTRC("DeviceRGB"));
         pDict->SetAtInteger(FX_BSTRC("BitsPerComponent"), 8);
         if ((iCompress & 0x03) == PDF_IMAGE_NO_COMPRESS) {
             dest_pitch = BitmapWidth * 3;
             opType = 2;
         } else {
             opType = 0;
         }
     }
+    FX_BOOL bDeleteMask = FALSE;
     const CFX_DIBitmap* pMaskBitmap = NULL;
     if (pBitmap->HasAlpha()) {
         pMaskBitmap = pBitmap->GetAlphaMask();
+        if (pMaskBitmap) {
+          bDeleteMask = TRUE;
+        }
     }
     if (!pMaskBitmap && pMask) {
         FXDIB_Format maskFormat = pMask->GetFormat();
         if (maskFormat == FXDIB_1bppMask || maskFormat == FXDIB_8bppMask) {
             pMaskBitmap = pMask;
         }
     }
     if (pMaskBitmap) {
         FX_INT32 maskWidth = pMaskBitmap->GetWidth();
         FX_INT32 maskHeight = pMaskBitmap->GetHeight();
         FX_LPBYTE mask_buf = NULL;
         FX_STRSIZE mask_size;
-        FX_BOOL bDeleteMask = TRUE;
         CPDF_Dictionary* pMaskDict = FX_NEW CPDF_Dictionary;
         pMaskDict->SetAtName(FX_BSTRC("Type"), FX_BSTRC("XObject"));
         pMaskDict->SetAtName(FX_BSTRC("Subtype"), FX_BSTRC("Image"));
         pMaskDict->SetAtInteger(FX_BSTRC("Width"), maskWidth);
         pMaskDict->SetAtInteger(FX_BSTRC("Height"), maskHeight);
         pMaskDict->SetAtName(FX_BSTRC("ColorSpace"), FX_BSTRC("DeviceGray"));
         pMaskDict->SetAtInteger(FX_BSTRC("BitsPerComponent"), 8);
         if (pMaskBitmap->GetBPP() == 8 && (iCompress & PDF_IMAGE_MASK_LOSSY_COMPRESS) != 0) {
             _DCTEncodeBitmap(pMaskDict, pMaskBitmap, pParam ? pParam->nQuality : 75, mask_buf, mask_size);
         } else if (pMaskBitmap->GetFormat() == FXDIB_1bppMask) {
@@ skipping 12 matching lines @@
                 int a, r, g, b;
                 ArgbDecode(*(pParam->pMatteColor), a, r, g, b);
                 CPDF_Array* pMatte = FX_NEW CPDF_Array;
                 pMatte->AddInteger(r);
                 pMatte->AddInteger(g);
                 pMatte->AddInteger(b);
                 pMaskDict->SetAt(FX_BSTRC("Matte"), pMatte);
             }
             pMaskStream = FX_NEW CPDF_Stream(mask_buf, mask_size, pMaskDict);
             m_pDocument->AddIndirectObject(pMaskStream);
-            bDeleteMask = FALSE;
             pDict->SetAtReference(FX_BSTRC("SMask"), m_pDocument, pMaskStream);
         }
-        if (pBitmap->HasAlpha()) {
+        if (bDeleteMask) {
             delete pMaskBitmap;
         }
     }
     FX_BOOL bStream = pFileWrite != NULL && pFileRead != NULL;
     if (opType == 0) {
         if (iCompress & PDF_IMAGE_LOSSLESS_COMPRESS) {
             if (pBitmap->GetBPP() == 1) {
                 _JBIG2EncodeBitmap(pDict, pBitmap, m_pDocument, dest_buf, dest_size, TRUE);
             }
         } else {
@@ skipping 105 matching lines @@
     m_Width = BitmapWidth;
     m_Height = BitmapHeight;
     if (dest_buf) {
         FX_Free(dest_buf);
     }
 }
 void CPDF_Image::ResetCache(CPDF_Page* pPage, const CFX_DIBitmap* pBitmap)
 {
     pPage->GetRenderCache()->ResetBitmap(m_pStream, pBitmap);
 }