Change CFX_FixedBufGrow to take a size_t.

Thanks to Qihoo 360 Vulcan Team for pointing this out.

Change-Id: Ib6dd77307b3759e54168127dc0e17aa42698d852
Reviewed-on: https://pdfium-review.googlesource.com/42830
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

core/fxcrt/cfx_fixedbufgrow.h

diff --git a/core/fxcrt/cfx_fixedbufgrow.h b/core/fxcrt/cfx_fixedbufgrow.h
index 55db8b2..558347e 100644
--- a/core/fxcrt/cfx_fixedbufgrow.h
+++ b/core/fxcrt/cfx_fixedbufgrow.h
@@ -11,10 +11,10 @@
 
 #include "core/fxcrt/fx_memory.h"
 
-template <class DataType, int FixedSize>
+template <class DataType, size_t FixedSize>
 class CFX_FixedBufGrow {
  public:
-  explicit CFX_FixedBufGrow(int data_size) {
+  explicit CFX_FixedBufGrow(size_t data_size) {
     if (data_size > FixedSize) {
       m_pGrowData.reset(FX_Alloc(DataType, data_size));
       return;