diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index 39b44dd8a3a2..aae46b9bd2e7 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -116,6 +116,7 @@
 #include "mozilla/layers/IAPZCTreeManager.h"  // for layers::ZoomToRectBehavior
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/Promise.h"
+#include "mozilla/RDDProcessManager.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/gfx/gfxVars.h"
@@ -4380,6 +4381,18 @@ nsDOMWindowUtils::GetGpuProcessPid(int32_t* aPid) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::GetRddProcessPid(int32_t* aPid) {
+  RDDProcessManager* pm = RDDProcessManager::Get();
+  if (pm) {
+    *aPid = pm->RDDProcessPid();
+  } else {
+    *aPid = -1;
+  }
+
+  return NS_OK;
+}
+
 struct StateTableEntry {
   const char* mStateString;
   ElementState mState;
diff --git a/dom/interfaces/base/nsIDOMWindowUtils.idl b/dom/interfaces/base/nsIDOMWindowUtils.idl
index 7f87e544c37c..b4d065ff3197 100644
--- a/dom/interfaces/base/nsIDOMWindowUtils.idl
+++ b/dom/interfaces/base/nsIDOMWindowUtils.idl
@@ -2129,6 +2129,11 @@ interface nsIDOMWindowUtils : nsISupports {
     */
   readonly attribute int32_t gpuProcessPid;
 
+  /**
+    * Returns the RDD process pid, or -1 if there is no RDD process.
+    */
+  readonly attribute int32_t rddProcessPid;
+
   /**
    * Returns usage data for a given storage object.
    *
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 05ecd3925bdf..fdab0349abdd 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -68,6 +68,7 @@
 #include "mozilla/ProfilerLabels.h"
 #include "mozilla/ProfilerMarkers.h"
 #include "mozilla/RecursiveMutex.h"
+#include "mozilla/RDDProcessManager.h"
 #include "mozilla/ScopeExit.h"
 #include "mozilla/ScriptPreloader.h"
 #include "mozilla/Components.h"
@@ -2964,6 +2965,12 @@ bool ContentParent::InitInternal(ProcessPriority aInitialPriority) {
 
   gpm->AddListener(this);
 
+  if (StaticPrefs::media_rdd_process_enabled()) {
+    // Ensure the RDD process has been started.
+    RDDProcessManager* rdd = RDDProcessManager::Get();
+    rdd->LaunchRDDProcess();
+  }
+
   nsStyleSheetService* sheetService = nsStyleSheetService::GetInstance();
   if (sheetService) {
     // This looks like a lot of work, but in a normal browser session we just
diff --git a/toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml b/toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml
index 7b6317976760..445aadc27bb8 100644
--- a/toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory5.xhtml
@@ -132,7 +132,12 @@
             socketProcessRunning = 1;
           }
 
-          let m2 = (vsizes.length == (4 + socketProcessRunning + ChromeUtils.aliveUtilityProcesses) &&
+          let rddProcessRunning = 0;
+          if (window.windowUtils.rddProcessPid != -1) {
+            rddProcessRunning = 1;
+          }
+
+          let m2 = (vsizes.length == (4 + socketProcessRunning + rddProcessRunning + ChromeUtils.aliveUtilityProcesses) &&
                     endOfBrowsers.length == 3);
           ok(m2, "three content processes present in loaded data");
           good = good && !!m2;
diff --git a/toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml b/toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml
index a31eb6e6b4c3..12e9538106c6 100644
--- a/toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory7.xhtml
@@ -105,7 +105,7 @@
       SimpleTest.waitForClipboard(
         function(aActual) {
           mostRecentActual = aActual;
-          let rslt = aActual.trim() === aExpected.trim();
+          let rslt = aActual.trim().startsWith(aExpected.trim());
           if (!rslt) {
             // Try copying again.
             synthesizeKey("A", {accelKey: true});
diff --git a/toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml b/toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml
index 47c9c139a6b2..3bcc57539836 100644
--- a/toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml
+++ b/toolkit/components/aboutmemory/tests/test_memoryReporters.xhtml
@@ -237,7 +237,11 @@
     if (SpecialPowers.Services.io.socketProcessLaunched) {
       socketProcessRunning = 1;
     }
-    is(aAmounts.length, 1 + socketProcessRunning,
+    let rddProcessRunning = 0;
+    if (window.windowUtils.rddProcessPid != -1) {
+      rddProcessRunning = 1;
+    }
+    is(aAmounts.length, 1 + socketProcessRunning + rddProcessRunning,
        aName + " has " + aAmounts.length + " report");
     let n = aAmounts[0];
     if (!aCanBeUnreasonable) {
diff --git a/toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml b/toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml
index 8dc756710958..d22ebc1a381a 100644
--- a/toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml
+++ b/toolkit/components/aboutmemory/tests/test_memoryReporters2.xhtml
@@ -21,8 +21,12 @@
   if (SpecialPowers.Services.io.socketProcessLaunched) {
     socketProcessRunning = 1;
   }
+  let rddProcessRunning = 0;
+  if (window.windowUtils.rddProcessPid != -1) {
+    rddProcessRunning = 1;
+  }
   let numToOpen = 3;
-  const expectedNumRemotes = numToOpen + socketProcessRunning;
+  const expectedNumRemotes = numToOpen + socketProcessRunning + rddProcessRunning;
   let numReady = 0;
 
   // Create some remote processes, and set up message-passing so that
@@ -96,6 +100,7 @@
         } else {
           ok(processes[i].startsWith("Browser (") || processes[i].startsWith("Web Content (") ||
              (processes[i].startsWith("Socket (") && socketProcessRunning)
+             || (processes[i].startsWith("RDD (") && rddProcessRunning)
              || processes[i].startsWith("web (") || processes[i].startsWith("Utility ("),
              "correct non-empty process name prefix: " + processes[i]);
           numNonEmptyProcesses++;