Merge to XFA: Various changes to JBig2 cache:

- Makes the cache be per-document
- Keys the cache on ObjNum and stream offset instead of keying on a pointer to the data (which can result in false cache hits).
- Makes it so the cache is only used for the globals stream.
- Reenable the cache.

R=dml@google.com
TBR=dml@google.com

BUG=pdfium:207

Review URL: https://codereview.chromium.org/1380243004 .

(cherry picked from commit f1b88e76134808f36f16b9e53a2e9dd89b12c8fd)

Review URL: https://codereview.chromium.org/1394373002 .

1 files changed, 5 insertions, 1 deletions

diff --git a/core/src/fxcodec/jbig2/JBig2_BitStream.h b/core/src/fxcodec/jbig2/JBig2_BitStream.h
index 9a3d8b0a18..c7c50b8c81 100644
--- a/core/src/fxcodec/jbig2/JBig2_BitStream.h
+++ b/core/src/fxcodec/jbig2/JBig2_BitStream.h
@@ -9,9 +9,11 @@
 
 #include "../../../include/fxcrt/fx_basic.h"
 
+class CPDF_StreamAcc;
+
 class CJBig2_BitStream {
  public:
-  CJBig2_BitStream(const uint8_t* pBuffer, FX_DWORD dwLength);
+  explicit CJBig2_BitStream(CPDF_StreamAcc* pSrcStream);
   ~CJBig2_BitStream();
 
   // TODO(thestig): readFoo() should return bool.
@@ -36,6 +38,7 @@ class CJBig2_BitStream {
   const uint8_t* getPointer() const;
   void offset(FX_DWORD dwOffset);
   FX_DWORD getByteLeft() const;
+  FX_DWORD getObjNum() const;
 
  private:
   void AdvanceBit();
@@ -46,6 +49,7 @@ class CJBig2_BitStream {
   FX_DWORD m_dwLength;
   FX_DWORD m_dwByteIdx;
   FX_DWORD m_dwBitIdx;
+  const FX_DWORD m_dwObjNum;
 
   CJBig2_BitStream(const CJBig2_BitStream&) = delete;
   void operator=(const CJBig2_BitStream&) = delete;