Fix a potential nullptr deref in CFX_MapPtrToPtr.

core/fxcrt/fx_basic_list.cpp

Index: core/fxcrt/fx_basic_list.cpp
diff --git a/core/fxcrt/fx_basic_list.cpp b/core/fxcrt/fx_basic_list.cpp
index 02afd471124acc57734c9f4c389d9cf60f93498e..800a22c09ba91b540140e7fcc0c4ee54cdd3e29c 100644
--- a/core/fxcrt/fx_basic_list.cpp
+++ b/core/fxcrt/fx_basic_list.cpp
@@ -76,7 +76,8 @@ void CFX_PtrList::FreeNode(CFX_PtrList::CNode* pNode) {
 void CFX_PtrList::RemoveAll() {
   m_nCount = 0;
   m_pNodeHead = m_pNodeTail = m_pNodeFree = NULL;

[Tom Sepez, 2016/05/19 17:02:01]

nit: one per pline.

[Lei Zhang, 2016/05/19 20:48:50]

Done.

-  m_pBlocks->FreeDataChain();
+  if (m_pBlocks)

[Tom Sepez, 2016/05/19 17:02:01]

Ah, idempotency.

Nit: As long as we're going to test it, we can conditionalize the NULL
assignment by this if statement.

[Lei Zhang, 2016/05/19 20:48:50]

Done.

+    m_pBlocks->FreeDataChain();
   m_pBlocks = NULL;

[Tom Sepez, 2016/05/19 17:02:01]

nit: nullptr, also above.

[Lei Zhang, 2016/05/19 20:48:50]

Done.

 }
 CFX_PtrList::CNode* CFX_PtrList::NewNode(CFX_PtrList::CNode* pPrev,