Use static_cast to get webrtc::Peerconnection in common workaround.

Bug: None
Change-Id: I523a22cfe69757e38922634d6054dca2d3bedb1a
No-Try: True
Reviewed-on: https://webrtc-review.googlesource.com/32640
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21239}
diff --git a/pc/peerconnection_datachannel_unittest.cc b/pc/peerconnection_datachannel_unittest.cc
index 918544c..02bac68 100644
--- a/pc/peerconnection_datachannel_unittest.cc
+++ b/pc/peerconnection_datachannel_unittest.cc
@@ -74,9 +74,10 @@
   }
 
   PeerConnection* GetInternalPeerConnection() {
-    auto* pci = reinterpret_cast<
-        PeerConnectionProxyWithInternal<PeerConnectionInterface>*>(pc());
-    return reinterpret_cast<PeerConnection*>(pci->internal());
+    auto* pci =
+        static_cast<PeerConnectionProxyWithInternal<PeerConnectionInterface>*>(
+            pc());
+    return static_cast<PeerConnection*>(pci->internal());
   }
 
  private: