Fix issue of localDescription and remoteDescription getter.

public/platform/WebRTCSessionDescription.h

Index: public/platform/WebRTCSessionDescription.h
diff --git a/public/platform/WebRTCSessionDescription.h b/public/platform/WebRTCSessionDescription.h
index a4b174614511243ea34c21bb596350decb9752b7..561f1be35dbf0afc61cfe8918e04b4d583254ab4 100644
--- a/public/platform/WebRTCSessionDescription.h
+++ b/public/platform/WebRTCSessionDescription.h
@@ -63,6 +63,14 @@ public:
         assign(other);
         return *this;
     }
+    bool operator==(const WebRTCSessionDescription& other)
+    {
+        return sdp() == other.sdp() && type() == other.type();
+    }
+    bool operator!=(const WebRTCSessionDescription& other)
+    {
+        return !(*this == other);
+    }
 
     BLINK_PLATFORM_EXPORT void assign(const WebRTCSessionDescription&);