Do slightly fewer casts with FPDFBitmap_GetBuffer() result.

Leave it as a void* and only cast it when needed.

Change-Id: I9ffaaf992ccd963bc1ba541d249d4a56d626a44b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/64072
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/samples/pdfium_test_write_helper.h b/samples/pdfium_test_write_helper.h
index f44c2e7..b53d555 100644
--- a/samples/pdfium_test_write_helper.h
+++ b/samples/pdfium_test_write_helper.h
@@ -16,7 +16,7 @@
 
 std::string WritePpm(const char* pdf_name,
                      int num,
-                     const void* buffer_void,
+                     void* buffer_void,
                      int stride,
                      int width,
                      int height);
@@ -24,7 +24,7 @@
 void WriteAnnot(FPDF_PAGE page, const char* pdf_name, int num);
 std::string WritePng(const char* pdf_name,
                      int num,
-                     const void* buffer_void,
+                     void* buffer,
                      int stride,
                      int width,
                      int height);
@@ -32,7 +32,7 @@
 #ifdef _WIN32
 std::string WriteBmp(const char* pdf_name,
                      int num,
-                     const void* buffer,
+                     void* buffer,
                      int stride,
                      int width,
                      int height);