diff --git a/dom/media/eme/MediaKeys.cpp b/dom/media/eme/MediaKeys.cpp
index fae4856c1a20..7209bd5c81eb 100644
--- a/dom/media/eme/MediaKeys.cpp
+++ b/dom/media/eme/MediaKeys.cpp
@@ -377,22 +377,23 @@ MediaKeys::Init(ErrorResult& aRv)
 class CrashHandler : public gmp::GeckoMediaPluginService::PluginCrashCallback
 {
 public:
-  CrashHandler(const nsACString& aPluginId,
+  CrashHandler(const uint32_t aPluginId,
                nsPIDOMWindow* aParentWindow,
                nsIDocument* aDocument)
     : gmp::GeckoMediaPluginService::PluginCrashCallback(aPluginId)
+    , mPluginId(aPluginId)
     , mParentWindowWeakPtr(do_GetWeakReference(aParentWindow))
     , mDocumentWeakPtr(do_GetWeakReference(aDocument))
   {
   }
 
-  virtual void Run(const nsACString& aPluginName, const nsAString& aPluginDumpId) override
+  virtual void Run(const nsACString& aPluginName) override
   {
     PluginCrashedEventInit init;
+    init.mPluginID = mPluginId;
     init.mBubbles = true;
     init.mCancelable = true;
     init.mGmpPlugin = true;
-    init.mPluginDumpID = aPluginDumpId;
     CopyUTF8toUTF16(aPluginName, init.mPluginName);
     init.mSubmittedCrashReport = false;
 
@@ -445,12 +446,13 @@ private:
     return true;
   }
 
+  uint32_t mPluginId;
   nsWeakPtr mParentWindowWeakPtr;
   nsWeakPtr mDocumentWeakPtr;
 };
 
 void
-MediaKeys::OnCDMCreated(PromiseId aId, const nsACString& aNodeId, const nsACString& aPluginId)
+MediaKeys::OnCDMCreated(PromiseId aId, const nsACString& aNodeId, const uint32_t aPluginId)
 {
   nsRefPtr<Promise> promise(RetrievePromise(aId));
   if (!promise) {
@@ -468,7 +470,7 @@ MediaKeys::OnCDMCreated(PromiseId aId, const nsACString& aNodeId, const nsACStri
                                         mKeySystem,
                                         MediaKeySystemStatus::Cdm_created);
 
-  if (!aPluginId.IsEmpty()) {
+  if (aPluginId) {
     // Prepare plugin crash reporter.
     nsRefPtr<gmp::GeckoMediaPluginService> service =
       gmp::GeckoMediaPluginService::GetGeckoMediaPluginService();
@@ -483,8 +485,8 @@ MediaKeys::OnCDMCreated(PromiseId aId, const nsACString& aNodeId, const nsACStri
       return;
     }
     service->AddPluginCrashCallback(new CrashHandler(aPluginId, mParent, doc));
-    EME_LOG("MediaKeys[%p]::OnCDMCreated() registered crash handler for pluginId '%s'",
-            this, aPluginId.Data());
+    EME_LOG("MediaKeys[%p]::OnCDMCreated() registered crash handler for pluginId '%i'",
+            this, aPluginId);
   }
 }
 
diff --git a/dom/media/eme/MediaKeys.h b/dom/media/eme/MediaKeys.h
index ca75703dac4a..3de34bac570d 100644
--- a/dom/media/eme/MediaKeys.h
+++ b/dom/media/eme/MediaKeys.h
@@ -81,7 +81,7 @@ public:
 
   // Called once a Init() operation succeeds.
   void OnCDMCreated(PromiseId aId,
-                    const nsACString& aNodeId, const nsACString& aPluginId);
+                    const nsACString& aNodeId, const uint32_t aPluginId);
 
   // Called once the CDM generates a sessionId while servicing a
   // MediaKeySession.generateRequest() or MediaKeySession.load() call,
diff --git a/dom/media/gmp/GMPContentParent.h b/dom/media/gmp/GMPContentParent.h
index c137b675fb8e..b85d2c7e39e2 100644
--- a/dom/media/gmp/GMPContentParent.h
+++ b/dom/media/gmp/GMPContentParent.h
@@ -51,11 +51,11 @@ public:
   {
     return mDisplayName;
   }
-  void SetPluginId(const nsCString& aPluginId)
+  void SetPluginId(const uint32_t aPluginId)
   {
     mPluginId = aPluginId;
   }
-  const nsCString& GetPluginId()
+  const uint32_t GetPluginId()
   {
     return mPluginId;
   }
@@ -92,7 +92,7 @@ private:
   nsCOMPtr<nsIThread> mGMPThread;
   nsRefPtr<GMPParent> mParent;
   nsCString mDisplayName;
-  nsCString mPluginId;
+  uint32_t mPluginId;
 };
 
 } // namespace gmp
diff --git a/dom/media/gmp/GMPDecryptorParent.cpp b/dom/media/gmp/GMPDecryptorParent.cpp
index efff6339c73b..d17339386085 100644
--- a/dom/media/gmp/GMPDecryptorParent.cpp
+++ b/dom/media/gmp/GMPDecryptorParent.cpp
@@ -29,7 +29,7 @@ GMPDecryptorParent::~GMPDecryptorParent()
 {
 }
 
-const nsACString&
+const uint32_t
 GMPDecryptorParent::GetPluginId() const
 {
   return mPluginId;
diff --git a/dom/media/gmp/GMPDecryptorParent.h b/dom/media/gmp/GMPDecryptorParent.h
index fb634672d7ef..df456e8033d6 100644
--- a/dom/media/gmp/GMPDecryptorParent.h
+++ b/dom/media/gmp/GMPDecryptorParent.h
@@ -29,7 +29,7 @@ public:
 
   // GMPDecryptorProxy
 
-  virtual const nsACString& GetPluginId() const override;
+  virtual const uint32_t GetPluginId() const override;
 
   virtual nsresult Init(GMPDecryptorProxyCallback* aCallback) override;
 
@@ -113,7 +113,7 @@ private:
   bool mShuttingDown;
   bool mActorDestroyed;
   nsRefPtr<GMPContentParent> mPlugin;
-  nsCString mPluginId;
+  uint32_t mPluginId;
   GMPDecryptorProxyCallback* mCallback;
 #ifdef DEBUG
   nsIThread* const mGMPThread;
diff --git a/dom/media/gmp/GMPDecryptorProxy.h b/dom/media/gmp/GMPDecryptorProxy.h
index bcc9fb2c4cad..b418c2f84a19 100644
--- a/dom/media/gmp/GMPDecryptorProxy.h
+++ b/dom/media/gmp/GMPDecryptorProxy.h
@@ -59,7 +59,7 @@ class GMPDecryptorProxy {
 public:
   ~GMPDecryptorProxy() {}
 
-  virtual const nsACString& GetPluginId() const = 0;
+  virtual const uint32_t GetPluginId() const = 0;
 
   virtual nsresult Init(GMPDecryptorProxyCallback* aCallback) = 0;
 
diff --git a/dom/media/gmp/GMPParent.cpp b/dom/media/gmp/GMPParent.cpp
index c3ea20342cb3..d54e50dff816 100644
--- a/dom/media/gmp/GMPParent.cpp
+++ b/dom/media/gmp/GMPParent.cpp
@@ -13,6 +13,7 @@
 #include "nsCharSeparatedTokenizer.h"
 #include "nsThreadUtils.h"
 #include "nsIRunnable.h"
+#include "nsIWritablePropertyBag2.h"
 #include "mozIGeckoMediaPluginService.h"
 #include "mozilla/ipc/GeckoChildProcessHost.h"
 #include "mozilla/SyncRunnable.h"
@@ -66,7 +67,7 @@ GMPParent::GMPParent()
 #endif
 {
   LOGD("GMPParent ctor");
-  mPluginId.AppendInt(GeckoChildProcessHost::GetUniqueID());
+  mPluginId = GeckoChildProcessHost::GetUniqueID();
 }
 
 GMPParent::~GMPParent()
@@ -499,23 +500,22 @@ GMPParent::GetCrashID(nsString& aResult)
 }
 
 static void
-GMPNotifyObservers(const nsACString& aPluginId, const nsACString& aPluginName, const nsAString& aPluginDumpId)
+GMPNotifyObservers(const uint32_t aPluginID, const nsACString& aPluginName, const nsAString& aPluginDumpID)
 {
   nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
-  if (obs) {
-    nsString id;
-    AppendUTF8toUTF16(aPluginId, id);
-    id.Append(NS_LITERAL_STRING(" "));
-    AppendUTF8toUTF16(aPluginName, id);
-    id.Append(NS_LITERAL_STRING(" "));
-    id.Append(aPluginDumpId);
-    obs->NotifyObservers(nullptr, "gmp-plugin-crash", id.Data());
+  nsCOMPtr<nsIWritablePropertyBag2> propbag =
+    do_CreateInstance("@mozilla.org/hash-property-bag;1");
+  if (obs && propbag) {
+    propbag->SetPropertyAsUint32(NS_LITERAL_STRING("pluginID"), aPluginID);
+    propbag->SetPropertyAsACString(NS_LITERAL_STRING("pluginName"), aPluginName);
+    propbag->SetPropertyAsAString(NS_LITERAL_STRING("pluginDumpID"), aPluginDumpID);
+    obs->NotifyObservers(propbag, "gmp-plugin-crash", nullptr);
   }
 
   nsRefPtr<gmp::GeckoMediaPluginService> service =
     gmp::GeckoMediaPluginService::GetGeckoMediaPluginService();
   if (service) {
-    service->RunPluginCrashCallbacks(aPluginId, aPluginName, aPluginDumpId);
+    service->RunPluginCrashCallbacks(aPluginID, aPluginName);
   }
 }
 #endif
@@ -820,7 +820,7 @@ GMPParent::GetVersion() const
   return mVersion;
 }
 
-const nsCString&
+const uint32_t
 GMPParent::GetPluginId() const
 {
   return mPluginId;
diff --git a/dom/media/gmp/GMPParent.h b/dom/media/gmp/GMPParent.h
index 8959c232d80d..cc2b834d824a 100644
--- a/dom/media/gmp/GMPParent.h
+++ b/dom/media/gmp/GMPParent.h
@@ -123,7 +123,7 @@ public:
 
   const nsCString& GetDisplayName() const;
   const nsCString& GetVersion() const;
-  const nsCString& GetPluginId() const;
+  const uint32_t GetPluginId() const;
 
   // Returns true if a plugin can be or is being used across multiple NodeIds.
   bool CanBeSharedCrossNodeIds() const;
@@ -192,7 +192,7 @@ private:
   nsCString mDisplayName; // name of plugin displayed to users
   nsCString mDescription; // description of plugin for display to users
   nsCString mVersion;
-  nsCString mPluginId;
+  uint32_t mPluginId;
   nsTArray<nsAutoPtr<GMPCapability>> mCapabilities;
   GMPProcessParent* mProcess;
   bool mDeleteProcessOnlyOnUnload;
diff --git a/dom/media/gmp/GMPService.cpp b/dom/media/gmp/GMPService.cpp
index 74b1c768caf1..e2553e05e47c 100644
--- a/dom/media/gmp/GMPService.cpp
+++ b/dom/media/gmp/GMPService.cpp
@@ -165,9 +165,8 @@ GeckoMediaPluginService::RemoveObsoletePluginCrashCallbacks()
   for (size_t i = mPluginCrashCallbacks.Length(); i != 0; --i) {
     nsRefPtr<PluginCrashCallback>& callback = mPluginCrashCallbacks[i - 1];
     if (!callback->IsStillValid()) {
-      LOGD(("%s::%s - Removing obsolete callback for pluginId %s",
-            __CLASS__, __FUNCTION__,
-            PromiseFlatCString(callback->PluginId()).get()));
+      LOGD(("%s::%s - Removing obsolete callback for pluginId %i",
+            __CLASS__, __FUNCTION__, callback->PluginId()));
       mPluginCrashCallbacks.RemoveElementAt(i - 1);
     }
   }
@@ -182,7 +181,7 @@ GeckoMediaPluginService::AddPluginCrashCallback(
 }
 
 void
-GeckoMediaPluginService::RemovePluginCrashCallbacks(const nsACString& aPluginId)
+GeckoMediaPluginService::RemovePluginCrashCallbacks(const uint32_t aPluginId)
 {
   RemoveObsoletePluginCrashCallbacks();
   for (size_t i = mPluginCrashCallbacks.Length(); i != 0; --i) {
@@ -194,24 +193,22 @@ GeckoMediaPluginService::RemovePluginCrashCallbacks(const nsACString& aPluginId)
 }
 
 void
-GeckoMediaPluginService::RunPluginCrashCallbacks(const nsACString& aPluginId,
-                                                 const nsACString& aPluginName,
-                                                 const nsAString& aPluginDumpId)
+GeckoMediaPluginService::RunPluginCrashCallbacks(const uint32_t aPluginId,
+                                                 const nsACString& aPluginName)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  LOGD(("%s::%s(%s)", __CLASS__, __FUNCTION__, aPluginId.Data()));
+  LOGD(("%s::%s(%i)", __CLASS__, __FUNCTION__, aPluginId));
   for (size_t i = mPluginCrashCallbacks.Length(); i != 0; --i) {
     nsRefPtr<PluginCrashCallback>& callback = mPluginCrashCallbacks[i - 1];
-    const nsACString& callbackPluginId = callback->PluginId();
+    const uint32_t callbackPluginId = callback->PluginId();
     if (!callback->IsStillValid()) {
-      LOGD(("%s::%s(%s) - Removing obsolete callback for pluginId %s",
-            __CLASS__, __FUNCTION__, aPluginId.Data(),
-            PromiseFlatCString(callback->PluginId()).get()));
+      LOGD(("%s::%s(%i) - Removing obsolete callback for pluginId %i",
+            __CLASS__, __FUNCTION__, aPluginId, callback->PluginId()));
       mPluginCrashCallbacks.RemoveElementAt(i - 1);
     } else if (callbackPluginId == aPluginId) {
-      LOGD(("%s::%s(%s) - Running #%u",
-          __CLASS__, __FUNCTION__, aPluginId.Data(), i - 1));
-      callback->Run(aPluginName, aPluginDumpId);
+      LOGD(("%s::%s(%i) - Running #%u",
+          __CLASS__, __FUNCTION__, aPluginId, i - 1));
+      callback->Run(aPluginName);
       mPluginCrashCallbacks.RemoveElementAt(i - 1);
     }
   }
diff --git a/dom/media/gmp/GMPService.h b/dom/media/gmp/GMPService.h
index 349f33af0026..d1fbfd6a6931 100644
--- a/dom/media/gmp/GMPService.h
+++ b/dom/media/gmp/GMPService.h
@@ -66,13 +66,13 @@ public:
   public:
     NS_INLINE_DECL_REFCOUNTING(PluginCrashCallback)
 
-    PluginCrashCallback(const nsACString& aPluginId)
+    PluginCrashCallback(const uint32_t aPluginId)
       : mPluginId(aPluginId)
     {
       MOZ_ASSERT(NS_IsMainThread());
     }
-    const nsACString& PluginId() const { return mPluginId; }
-    virtual void Run(const nsACString& aPluginName, const nsAString& aPluginDumpId) = 0;
+    const uint32_t PluginId() const { return mPluginId; }
+    virtual void Run(const nsACString& aPluginName) = 0;
     virtual bool IsStillValid() = 0; // False if callback has become useless.
   protected:
     virtual ~PluginCrashCallback()
@@ -80,14 +80,13 @@ public:
       MOZ_ASSERT(NS_IsMainThread());
     }
   private:
-    const nsCString mPluginId;
+    const uint32_t mPluginId;
   };
   void RemoveObsoletePluginCrashCallbacks(); // Called from add/remove/run.
   void AddPluginCrashCallback(nsRefPtr<PluginCrashCallback> aPluginCrashCallback);
-  void RemovePluginCrashCallbacks(const nsACString& aPluginId);
-  void RunPluginCrashCallbacks(const nsACString& aPluginId,
-                               const nsACString& aPluginName,
-                               const nsAString& aPluginDumpId);
+  void RemovePluginCrashCallbacks(const uint32_t aPluginId);
+  void RunPluginCrashCallbacks(const uint32_t aPluginId,
+                               const nsACString& aPluginName);
 
 protected:
   GeckoMediaPluginService();
diff --git a/dom/media/gmp/GMPServiceChild.cpp b/dom/media/gmp/GMPServiceChild.cpp
index 1c29f6fac527..abb126c87434 100644
--- a/dom/media/gmp/GMPServiceChild.cpp
+++ b/dom/media/gmp/GMPServiceChild.cpp
@@ -82,7 +82,7 @@ public:
 
     base::ProcessId otherProcess;
     nsCString displayName;
-    nsCString pluginId;
+    uint32_t pluginId;
     bool ok = aGMPServiceChild->SendLoadGMP(mNodeId, mAPI, mTags,
                                             alreadyBridgedTo, &otherProcess,
                                             &displayName, &pluginId);
diff --git a/dom/media/gmp/GMPServiceParent.cpp b/dom/media/gmp/GMPServiceParent.cpp
index ac3be2537d5b..e40b01c1a587 100644
--- a/dom/media/gmp/GMPServiceParent.cpp
+++ b/dom/media/gmp/GMPServiceParent.cpp
@@ -1435,7 +1435,7 @@ GMPServiceParent::RecvLoadGMP(const nsCString& aNodeId,
                               nsTArray<ProcessId>&& aAlreadyBridgedTo,
                               ProcessId* aId,
                               nsCString* aDisplayName,
-                              nsCString* aPluginId)
+                              uint32_t* aPluginId)
 {
   nsRefPtr<GMPParent> gmp = mService->SelectPluginForAPI(aNodeId, aAPI, aTags);
 
diff --git a/dom/media/gmp/GMPServiceParent.h b/dom/media/gmp/GMPServiceParent.h
index 044433ea0675..c636ffc21c46 100644
--- a/dom/media/gmp/GMPServiceParent.h
+++ b/dom/media/gmp/GMPServiceParent.h
@@ -193,7 +193,7 @@ public:
                            nsTArray<ProcessId>&& aAlreadyBridgedTo,
                            base::ProcessId* aID,
                            nsCString* aDisplayName,
-                           nsCString* aPluginId) override;
+                           uint32_t* aPluginId) override;
   virtual bool RecvGetGMPNodeId(const nsString& aOrigin,
                                 const nsString& aTopLevelOrigin,
                                 const bool& aInPrivateBrowsing,
diff --git a/dom/media/gmp/GMPVideoEncoderProxy.h b/dom/media/gmp/GMPVideoEncoderProxy.h
index b1141e684adb..747aa5d748c1 100644
--- a/dom/media/gmp/GMPVideoEncoderProxy.h
+++ b/dom/media/gmp/GMPVideoEncoderProxy.h
@@ -46,7 +46,7 @@ public:
   virtual GMPErr SetChannelParameters(uint32_t aPacketLoss, uint32_t aRTT) = 0;
   virtual GMPErr SetRates(uint32_t aNewBitRate, uint32_t aFrameRate) = 0;
   virtual GMPErr SetPeriodicKeyFrames(bool aEnable) = 0;
-  virtual const uint64_t ParentID() = 0;
+  virtual const uint32_t ParentID() = 0;
 
   // Call to tell GMP/plugin the consumer will no longer use this
   // interface/codec.
diff --git a/dom/media/gmp/PGMPService.ipdl b/dom/media/gmp/PGMPService.ipdl
index 80d24f7a6aae..bdfc40be09a7 100644
--- a/dom/media/gmp/PGMPService.ipdl
+++ b/dom/media/gmp/PGMPService.ipdl
@@ -17,7 +17,7 @@ sync protocol PGMPService
 parent:
   sync LoadGMP(nsCString nodeId, nsCString api, nsCString[] tags,
                ProcessId[] alreadyBridgedTo)
-    returns (ProcessId id, nsCString displayName, nsCString pluginId);
+    returns (ProcessId id, nsCString displayName, uint32_t pluginId);
   sync GetGMPNodeId(nsString origin, nsString topLevelOrigin,
                     bool inPrivateBrowsing)
     returns (nsCString id);
diff --git a/dom/webidl/PeerConnectionImpl.webidl b/dom/webidl/PeerConnectionImpl.webidl
index 65870c810ded..7061c7a2fa3f 100644
--- a/dom/webidl/PeerConnectionImpl.webidl
+++ b/dom/webidl/PeerConnectionImpl.webidl
@@ -63,7 +63,7 @@ interface PeerConnectionImpl  {
   void close();
 
   /* Notify DOM window if this plugin crash is ours. */
-  boolean pluginCrash(unsigned long long pluginId, DOMString name, DOMString pluginDumpID);
+  boolean pluginCrash(unsigned long long pluginId, DOMString name);
 
   /* Attributes */
   [Constant]
diff --git a/dom/webidl/PluginCrashedEvent.webidl b/dom/webidl/PluginCrashedEvent.webidl
index b2056d7bb92c..8eed7244e519 100644
--- a/dom/webidl/PluginCrashedEvent.webidl
+++ b/dom/webidl/PluginCrashedEvent.webidl
@@ -7,6 +7,7 @@
 [Constructor(DOMString type, optional PluginCrashedEventInit eventInitDict), ChromeOnly]
 interface PluginCrashedEvent : Event
 {
+  readonly attribute unsigned long pluginID;
   readonly attribute DOMString pluginDumpID;
   readonly attribute DOMString pluginName;
   readonly attribute DOMString? browserDumpID;
@@ -17,6 +18,7 @@ interface PluginCrashedEvent : Event
 
 dictionary PluginCrashedEventInit : EventInit
 {
+  unsigned long pluginID = 0;
   DOMString pluginDumpID = "";
   DOMString pluginName = "";
   DOMString? browserDumpID = null;
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
index acb9d4af2429..9988d7b5b568 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
@@ -2290,9 +2290,8 @@ PeerConnectionImpl::Close()
 }
 
 bool
-PeerConnectionImpl::PluginCrash(uint64_t aPluginID,
-                                const nsAString& aPluginName,
-                                const nsAString& aPluginDumpID)
+PeerConnectionImpl::PluginCrash(uint32_t aPluginID,
+                                const nsAString& aPluginName)
 {
   // fire an event to the DOM window if this is "ours"
   bool result = mMedia ? mMedia->AnyCodecHasPluginID(aPluginID) : false;
@@ -2310,7 +2309,7 @@ PeerConnectionImpl::PluginCrash(uint64_t aPluginID,
   }
 
   PluginCrashedEventInit init;
-  init.mPluginDumpID = aPluginDumpID;
+  init.mPluginID = aPluginID;
   init.mPluginName = aPluginName;
   init.mSubmittedCrashReport = false;
   init.mGmpPlugin = true;
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
index c543fb24ae21..d3611abbe067 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
@@ -526,9 +526,8 @@ public:
     rv = Close();
   }
 
-  bool PluginCrash(uint64_t aPluginID,
-                   const nsAString& aPluginName,
-                   const nsAString& aPluginDumpID);
+  bool PluginCrash(uint32_t aPluginID,
+                   const nsAString& aPluginName);
 
   nsresult InitializeDataChannel();