Injects FrameEncryptorInterface into RtpSender.

This change injects the FrameEncryptorInterface and the FrameDecryptorInterface
into the RtpSenderInterface and RtpReceiverInterface respectively. This is the
second stage of the injection. In a follow up CL non owning pointers to these
values will be passed down into the media channel.

This change also updates the corresponding mock files.

Bug: webrtc:9681
Change-Id: I964084fc270e10af9d1127979e713493e6fbba7d
Reviewed-on: https://webrtc-review.googlesource.com/96625
Commit-Queue: Benjamin Wright <benwright@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24489}

pc/test/mock_rtpsenderinternal.h

diff --git a/pc/test/mock_rtpsenderinternal.h b/pc/test/mock_rtpsenderinternal.h
index 3ddffec..8e2bf73 100644
--- a/pc/test/mock_rtpsenderinternal.h
+++ b/pc/test/mock_rtpsenderinternal.h
@@ -32,6 +32,10 @@
   MOCK_METHOD0(GetParameters, RtpParameters());
   MOCK_METHOD1(SetParameters, RTCError(const RtpParameters&));
   MOCK_CONST_METHOD0(GetDtmfSender, rtc::scoped_refptr<DtmfSenderInterface>());
+  MOCK_METHOD1(SetFrameEncryptor,
+               void(rtc::scoped_refptr<FrameEncryptorInterface>));
+  MOCK_CONST_METHOD0(GetFrameEncryptor,
+                     rtc::scoped_refptr<FrameEncryptorInterface>());
 
   // RtpSenderInternal methods.
   MOCK_METHOD1(SetVoiceMediaChannel, void(cricket::VoiceMediaChannel*));