Fix CFX_RetainPtr move-assign semantics.

Ensure moved value becomes a nullptr after the move.
Update comment while we're at it.

Change-Id: I7a2999d5f5c5142cc7826cd7880b1e2317b5445f
Reviewed-on: https://pdfium-review.googlesource.com/3163
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/core/fxcrt/cfx_retain_ptr.h b/core/fxcrt/cfx_retain_ptr.h
index 0267ae04cd..5db384f334 100644
--- a/core/fxcrt/cfx_retain_ptr.h
+++ b/core/fxcrt/cfx_retain_ptr.h
@@ -44,7 +44,7 @@ class CFX_RetainPtr {
   T* Get() const { return m_pObj.get(); }
   void Swap(CFX_RetainPtr& that) { m_pObj.swap(that.m_pObj); }
 
-  // TODO(tsepez): temporary scaffolding, to be removed.
+  // Useful for passing notion of object ownership across a C API.
   T* Leak() { return m_pObj.release(); }
   void Unleak(T* ptr) { m_pObj.reset(ptr); }
 
@@ -54,6 +54,11 @@ class CFX_RetainPtr {
     return *this;
   }
 
+  CFX_RetainPtr& operator=(CFX_RetainPtr&& that) {
+    m_pObj.reset(that.Leak());
+    return *this;
+  }
+
   bool operator==(const CFX_RetainPtr& that) const {
     return Get() == that.Get();
   }