Reland "Set session error if SetLocal/RemoteDescription ever fails"

Original change's description:
> Set session error if SetLocal/RemoteDescription ever fails
> 
> This changes SetLocalDescription/SetRemoteDescription to set a
> session error which will cause any future calls to fail early if
> there is an error when applying a session description.
> 
> This is needed since until better error recovery is implemented
> failing a call to SetLocalDescription or SetRemoteDescription
> could leave the PeerConnection in an inconsistent state.
> 
> Bug: chromium:800775
> Change-Id: If06fd73d6e902af15d072dc562bbe830d3b11ad5
> Reviewed-on: https://webrtc-review.googlesource.com/54061
> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> Commit-Queue: Steve Anton <steveanton@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22061}

Bug: chromium:800775
Change-Id: I0016108264e013452e9d34239c012baf23240e99
Reviewed-on: https://webrtc-review.googlesource.com/54720
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22067}
diff --git a/pc/peerconnection_media_unittest.cc b/pc/peerconnection_media_unittest.cc
index 3a88e80..8d1dd76 100644
--- a/pc/peerconnection_media_unittest.cc
+++ b/pc/peerconnection_media_unittest.cc
@@ -918,9 +918,8 @@
   ASSERT_FALSE(caller->SetRemoteDescription(callee->CreateAnswerAndSetAsLocal(),
                                             &error));
   EXPECT_EQ(
-      "Failed to set remote answer sdp: Session error code: ERROR_CONTENT. "
-      "Session error description: Failed to set remote video description send "
-      "parameters..",
+      "Failed to set remote answer sdp: Failed to set remote video description "
+      "send parameters.",
       error);
 }