diff --git a/webrtc/api/peerconnection.cc b/webrtc/api/peerconnection.cc
index a47b2f2d8c..e1f19adf3e 100644
--- a/webrtc/api/peerconnection.cc
+++ b/webrtc/api/peerconnection.cc
@@ -432,6 +432,25 @@ void SetChannelOnSendersAndReceivers(CHANNEL* channel,
 
 namespace webrtc {
 
+static const char* const kRtcErrorNames[] = {
+    "NONE",
+    "UNSUPPORTED_PARAMETER",
+    "INVALID_PARAMETER",
+    "INVALID_RANGE",
+    "SYNTAX_ERROR",
+    "INVALID_STATE",
+    "INVALID_MODIFICATION",
+    "NETWORK_ERROR",
+    "INTERNAL_ERROR",
+};
+
+std::ostream& operator<<(std::ostream& stream, RtcError error) {
+  int index = static_cast<int>(error);
+  RTC_CHECK(index < static_cast<int>(sizeof(kRtcErrorNames) /
+                                     sizeof(kRtcErrorNames[0])));
+  return stream << kRtcErrorNames[index];
+}
+
 // Generate a RTCP CNAME when a PeerConnection is created.
 std::string GenerateRtcpCname() {
   std::string cname;
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index 54fae2b711..a6557562a4 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -52,6 +52,7 @@
 #define WEBRTC_API_PEERCONNECTIONINTERFACE_H_
 
 #include <memory>
+#include <ostream>
 #include <string>
 #include <utility>
 #include <vector>
@@ -140,6 +141,44 @@ class MetricsObserverInterface : public rtc::RefCountInterface {
 
 typedef MetricsObserverInterface UMAObserver;
 
+// Enumeration to represent distinct classes of errors that an application
+// may wish to act upon differently. These roughly map to DOMExceptions in
+// the web API, as described in the comments below.
+enum class RtcError {
+  // No error.
+  NONE,
+  // A supplied parameter is valid, but currently unsupported.
+  // Maps to InvalidAccessError DOMException.
+  UNSUPPORTED_PARAMETER,
+  // General error indicating that a supplied parameter is invalid.
+  // Maps to InvalidAccessError or TypeError DOMException depending on context.
+  INVALID_PARAMETER,
+  // Slightly more specific than INVALID_PARAMETER; a parameter's value was
+  // outside the allowed range.
+  // Maps to RangeError DOMException.
+  INVALID_RANGE,
+  // Slightly more specific than INVALID_PARAMETER; an error occurred while
+  // parsing string input.
+  // Maps to SyntaxError DOMException.
+  SYNTAX_ERROR,
+  // The object does not support this operation in its current state.
+  // Maps to InvalidStateError DOMException.
+  INVALID_STATE,
+  // An attempt was made to modify the object in an invalid way.
+  // Maps to InvalidModificationError DOMException.
+  INVALID_MODIFICATION,
+  // An error occurred within an underlying network protocol.
+  // Maps to NetworkError DOMException.
+  NETWORK_ERROR,
+  // The operation failed due to an internal error.
+  // Maps to OperationError DOMException.
+  INTERNAL_ERROR,
+};
+
+// Outputs the error as a friendly string.
+// Update this method when adding a new error type.
+std::ostream& operator<<(std::ostream& stream, RtcError error);
+
 class PeerConnectionInterface : public rtc::RefCountInterface {
  public:
   // See http://dev.w3.org/2011/webrtc/editor/webrtc.html#state-definitions .
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index d673b4174a..cfba3e67ec 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -9,6 +9,7 @@
  */
 
 #include <memory>
+#include <sstream>
 #include <string>
 #include <utility>
 
@@ -2989,3 +2990,11 @@ TEST(CreateSessionOptionsTest, MediaConstraintsInAnswer) {
   EXPECT_TRUE(updated_answer_options.has_audio());
   EXPECT_TRUE(updated_answer_options.has_video());
 }
+
+TEST(RtcErrorTest, OstreamOperator) {
+  std::ostringstream oss;
+  oss << webrtc::RtcError::NONE << ' '
+      << webrtc::RtcError::INVALID_PARAMETER << ' '
+      << webrtc::RtcError::INTERNAL_ERROR;
+  EXPECT_EQ("NONE INVALID_PARAMETER INTERNAL_ERROR", oss.str());
+}