Check for empty streams earlier in CPDF_StreamAcc::LoadAllData().

Change-Id: I91c8d7d837e4c2104d56d725c16a28d49399aaca
Reviewed-on: https://pdfium-review.googlesource.com/42592
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

core/fpdfapi/parser/cpdf_stream_acc.cpp

diff --git a/core/fpdfapi/parser/cpdf_stream_acc.cpp b/core/fpdfapi/parser/cpdf_stream_acc.cpp
index 4614dae..dc6b180 100644
--- a/core/fpdfapi/parser/cpdf_stream_acc.cpp
+++ b/core/fpdfapi/parser/cpdf_stream_acc.cpp
@@ -27,16 +27,17 @@
   if (!m_pStream)
     return;
 
-  bool bProcessRawData = bRawAccess || !m_pStream->HasFilter();
-  if (bProcessRawData && m_pStream->IsMemoryBased()) {
-    m_dwSize = m_pStream->GetRawSize();
-    m_pData = m_pStream->GetInMemoryRawData();
-    return;
-  }
   uint32_t dwSrcSize = m_pStream->GetRawSize();
   if (dwSrcSize == 0)
     return;
 
+  bool bProcessRawData = bRawAccess || !m_pStream->HasFilter();
+  if (bProcessRawData && m_pStream->IsMemoryBased()) {
+    m_pData = m_pStream->GetInMemoryRawData();
+    m_dwSize = dwSrcSize;
+    return;
+  }
+
   uint8_t* pSrcData;
   if (m_pStream->IsMemoryBased()) {
     pSrcData = m_pStream->GetInMemoryRawData();