diff --git a/pc/BUILD.gn b/pc/BUILD.gn
index f36505b153..94b0842eab 100644
--- a/pc/BUILD.gn
+++ b/pc/BUILD.gn
@@ -41,6 +41,7 @@ rtc_library("rtc_pc_base") {
   visibility = [ "*" ]
   defines = []
   sources = [
+    "bundle_manager.cc",
     "bundle_manager.h",
     "channel.cc",
     "channel.h",
diff --git a/pc/bundle_manager.cc b/pc/bundle_manager.cc
new file mode 100644
index 0000000000..0228635998
--- /dev/null
+++ b/pc/bundle_manager.cc
@@ -0,0 +1,49 @@
+/*
+ *  Copyright 2021 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "pc/bundle_manager.h"
+
+namespace webrtc {
+
+void BundleManager::Update(const cricket::SessionDescription* description) {
+  bundle_groups_.clear();
+  for (const cricket::ContentGroup* new_bundle_group :
+       description->GetGroupsByName(cricket::GROUP_TYPE_BUNDLE)) {
+    bundle_groups_.push_back(
+        std::make_unique<cricket::ContentGroup>(*new_bundle_group));
+  }
+}
+
+void BundleManager::DeleteMid(const cricket::ContentGroup* bundle_group,
+                              const std::string& mid) {
+  // Remove the rejected content from the |bundle_group|.
+  // The const pointer arg is used to identify the group, we verify
+  // it before we use it to make a modification.
+  auto bundle_group_it = std::find_if(
+      bundle_groups_.begin(), bundle_groups_.end(),
+      [bundle_group](std::unique_ptr<cricket::ContentGroup>& group) {
+        return bundle_group == group.get();
+      });
+  RTC_DCHECK(bundle_group_it != bundle_groups_.end());
+  (*bundle_group_it)->RemoveContentName(mid);
+}
+
+void BundleManager::DeleteGroup(const cricket::ContentGroup* bundle_group) {
+  // Delete the BUNDLE group.
+  auto bundle_group_it = std::find_if(
+      bundle_groups_.begin(), bundle_groups_.end(),
+      [bundle_group](std::unique_ptr<cricket::ContentGroup>& group) {
+        return bundle_group == group.get();
+      });
+  RTC_DCHECK(bundle_group_it != bundle_groups_.end());
+  bundle_groups_.erase(bundle_group_it);
+}
+
+}  // namespace webrtc
diff --git a/pc/bundle_manager.h b/pc/bundle_manager.h
index 3cbf351bbc..2e2aa77f6d 100644
--- a/pc/bundle_manager.h
+++ b/pc/bundle_manager.h
@@ -12,6 +12,7 @@
 #define PC_BUNDLE_MANAGER_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "pc/session_description.h"
@@ -22,7 +23,7 @@ namespace webrtc {
 
 // This is a work-in-progress. Planned steps:
 // 1) Move all Bundle-related data structures from JsepTransport
-//  into this class.
+//    into this class.
 // 2) Move all Bundle-related functions into this class.
 // 3) Move remaining Bundle-related logic into this class.
 //    Make data members private.
@@ -35,12 +36,16 @@ class BundleManager {
       const {
     return bundle_groups_;
   }
-  std::vector<std::unique_ptr<cricket::ContentGroup>>& bundle_groups() {
-    return bundle_groups_;
-  }
+  // Update the groups description. This completely replaces the group
+  // description with the one from the SessionDescription.
+  void Update(const cricket::SessionDescription* description);
+  // Delete a MID from the group that contains it.
+  void DeleteMid(const cricket::ContentGroup* bundle_group,
+                 const std::string& mid);
+  // Delete a group.
+  void DeleteGroup(const cricket::ContentGroup* bundle_group);
 
  private:
-  // Use unique_ptr<> to get a stable address.
   std::vector<std::unique_ptr<cricket::ContentGroup>> bundle_groups_;
 };
 
diff --git a/pc/jsep_transport_controller.cc b/pc/jsep_transport_controller.cc
index 69e71d961a..413c940da8 100644
--- a/pc/jsep_transport_controller.cc
+++ b/pc/jsep_transport_controller.cc
@@ -778,11 +778,7 @@ RTCError JsepTransportController::ValidateAndMaybeUpdateBundleGroups(
   }
 
   if (ShouldUpdateBundleGroup(type, description)) {
-    bundles_.bundle_groups().clear();
-    for (const cricket::ContentGroup* new_bundle_group : new_bundle_groups) {
-      bundles_.bundle_groups().push_back(
-          std::make_unique<cricket::ContentGroup>(*new_bundle_group));
-    }
+    bundles_.Update(description);
   }
 
   for (const auto& bundle_group : bundles_.bundle_groups()) {
@@ -850,18 +846,12 @@ void JsepTransportController::HandleRejectedContent(
       established_bundle_groups_by_mid.erase(it);
     }
     // Delete the BUNDLE group.
-    auto bundle_group_it = std::find_if(
-        bundles_.bundle_groups().begin(), bundles_.bundle_groups().end(),
-        [bundle_group](std::unique_ptr<cricket::ContentGroup>& group) {
-          return bundle_group == group.get();
-        });
-    RTC_DCHECK(bundle_group_it != bundles_.bundle_groups().end());
-    bundles_.bundle_groups().erase(bundle_group_it);
+    bundles_.DeleteGroup(bundle_group);
   } else {
     RemoveTransportForMid(content_info.name);
     if (bundle_group) {
       // Remove the rejected content from the |bundle_group|.
-      bundle_group->RemoveContentName(content_info.name);
+      bundles_.DeleteMid(bundle_group, content_info.name);
     }
   }
   MaybeDestroyJsepTransport(content_info.name);