Adding getParameters/setParameters APIs to RtpReceiver.

This is similar to how a "receive" method is used to apply
RtpParameters to an RtpReceiver in ORTC. Currently, SetParameters
doesn't allow changing the parameters, so the main use of the API is
to retrieve the set of configured codecs. But other uses will likely
be made possible in the future.

R=glaznev@webrtc.org, pthatcher@webrtc.org, tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1917193008 .

Cr-Commit-Position: refs/heads/master@{#12761}
diff --git a/webrtc/media/base/fakemediaengine.h b/webrtc/media/base/fakemediaengine.h
index 5db783c..bde5843 100644
--- a/webrtc/media/base/fakemediaengine.h
+++ b/webrtc/media/base/fakemediaengine.h
@@ -99,13 +99,14 @@
       return false;
     }
     send_streams_.push_back(sp);
-    rtp_parameters_[sp.first_ssrc()] = CreateRtpParametersWithOneEncoding();
+    rtp_send_parameters_[sp.first_ssrc()] =
+        CreateRtpParametersWithOneEncoding();
     return true;
   }
   virtual bool RemoveSendStream(uint32_t ssrc) {
-    auto parameters_iterator = rtp_parameters_.find(ssrc);
-    if (parameters_iterator != rtp_parameters_.end()) {
-      rtp_parameters_.erase(parameters_iterator);
+    auto parameters_iterator = rtp_send_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_send_parameters_.end()) {
+      rtp_send_parameters_.erase(parameters_iterator);
     }
     return RemoveStreamBySsrc(&send_streams_, ssrc);
   }
@@ -115,23 +116,49 @@
       return false;
     }
     receive_streams_.push_back(sp);
+    rtp_receive_parameters_[sp.first_ssrc()] =
+        CreateRtpParametersWithOneEncoding();
     return true;
   }
   virtual bool RemoveRecvStream(uint32_t ssrc) {
+    auto parameters_iterator = rtp_receive_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_receive_parameters_.end()) {
+      rtp_receive_parameters_.erase(parameters_iterator);
+    }
     return RemoveStreamBySsrc(&receive_streams_, ssrc);
   }
 
-  virtual webrtc::RtpParameters GetRtpParameters(uint32_t ssrc) const {
-    auto parameters_iterator = rtp_parameters_.find(ssrc);
-    if (parameters_iterator != rtp_parameters_.end()) {
+  virtual webrtc::RtpParameters GetRtpSendParameters(uint32_t ssrc) const {
+    auto parameters_iterator = rtp_send_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_send_parameters_.end()) {
       return parameters_iterator->second;
     }
     return webrtc::RtpParameters();
   }
-  virtual bool SetRtpParameters(uint32_t ssrc,
-                                const webrtc::RtpParameters& parameters) {
-    auto parameters_iterator = rtp_parameters_.find(ssrc);
-    if (parameters_iterator != rtp_parameters_.end()) {
+  virtual bool SetRtpSendParameters(uint32_t ssrc,
+                                    const webrtc::RtpParameters& parameters) {
+    auto parameters_iterator = rtp_send_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_send_parameters_.end()) {
+      parameters_iterator->second = parameters;
+      return true;
+    }
+    // Replicate the behavior of the real media channel: return false
+    // when setting parameters for unknown SSRCs.
+    return false;
+  }
+
+  virtual webrtc::RtpParameters GetRtpReceiveParameters(uint32_t ssrc) const {
+    auto parameters_iterator = rtp_receive_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_receive_parameters_.end()) {
+      return parameters_iterator->second;
+    }
+    return webrtc::RtpParameters();
+  }
+  virtual bool SetRtpReceiveParameters(
+      uint32_t ssrc,
+      const webrtc::RtpParameters& parameters) {
+    auto parameters_iterator = rtp_receive_parameters_.find(ssrc);
+    if (parameters_iterator != rtp_receive_parameters_.end()) {
       parameters_iterator->second = parameters;
       return true;
     }
@@ -243,7 +270,8 @@
   std::vector<StreamParams> send_streams_;
   std::vector<StreamParams> receive_streams_;
   std::set<uint32_t> muted_streams_;
-  std::map<uint32_t, webrtc::RtpParameters> rtp_parameters_;
+  std::map<uint32_t, webrtc::RtpParameters> rtp_send_parameters_;
+  std::map<uint32_t, webrtc::RtpParameters> rtp_receive_parameters_;
   bool fail_set_send_codecs_;
   bool fail_set_recv_codecs_;
   uint32_t send_ssrc_;