diff --git a/dom/media/gmp/GMPDecryptorParent.cpp b/dom/media/gmp/GMPDecryptorParent.cpp
index d17339386085..6c127461821e 100644
--- a/dom/media/gmp/GMPDecryptorParent.cpp
+++ b/dom/media/gmp/GMPDecryptorParent.cpp
@@ -16,25 +16,19 @@ GMPDecryptorParent::GMPDecryptorParent(GMPContentParent* aPlugin)
   , mShuttingDown(false)
   , mActorDestroyed(false)
   , mPlugin(aPlugin)
+  , mPluginId(aPlugin->GetPluginId())
   , mCallback(nullptr)
 #ifdef DEBUG
   , mGMPThread(aPlugin->GMPThread())
 #endif
 {
   MOZ_ASSERT(mPlugin && mGMPThread);
-  mPluginId = aPlugin->GetPluginId();
 }
 
 GMPDecryptorParent::~GMPDecryptorParent()
 {
 }
 
-const uint32_t
-GMPDecryptorParent::GetPluginId() const
-{
-  return mPluginId;
-}
-
 nsresult
 GMPDecryptorParent::Init(GMPDecryptorProxyCallback* aCallback)
 {
diff --git a/dom/media/gmp/GMPDecryptorParent.h b/dom/media/gmp/GMPDecryptorParent.h
index df456e8033d6..dfee56d5e862 100644
--- a/dom/media/gmp/GMPDecryptorParent.h
+++ b/dom/media/gmp/GMPDecryptorParent.h
@@ -29,7 +29,7 @@ public:
 
   // GMPDecryptorProxy
 
-  virtual const uint32_t GetPluginId() const override;
+  virtual const uint32_t GetPluginId() const override { return mPluginId; }
 
   virtual nsresult Init(GMPDecryptorProxyCallback* aCallback) override;
 
diff --git a/dom/media/gmp/GMPVideoDecoderParent.cpp b/dom/media/gmp/GMPVideoDecoderParent.cpp
index ef695ed00d26..4be47114842c 100644
--- a/dom/media/gmp/GMPVideoDecoderParent.cpp
+++ b/dom/media/gmp/GMPVideoDecoderParent.cpp
@@ -46,6 +46,7 @@ GMPVideoDecoderParent::GMPVideoDecoderParent(GMPContentParent* aPlugin)
   , mPlugin(aPlugin)
   , mCallback(nullptr)
   , mVideoHost(this)
+  , mPluginId(aPlugin->GetPluginId())
 {
   MOZ_ASSERT(mPlugin);
 }
diff --git a/dom/media/gmp/GMPVideoDecoderParent.h b/dom/media/gmp/GMPVideoDecoderParent.h
index f07b57fdfaff..9b54403146f4 100644
--- a/dom/media/gmp/GMPVideoDecoderParent.h
+++ b/dom/media/gmp/GMPVideoDecoderParent.h
@@ -44,7 +44,7 @@ public:
                           int64_t aRenderTimeMs = -1) override;
   virtual nsresult Reset() override;
   virtual nsresult Drain() override;
-  virtual const uint64_t ParentID() override { return reinterpret_cast<uint64_t>(mPlugin.get()); }
+  virtual const uint32_t GetPluginId() const override { return mPluginId; }
   virtual const nsCString& GetDisplayName() const override;
 
   // GMPSharedMemManager
@@ -85,6 +85,7 @@ private:
   nsRefPtr<GMPContentParent> mPlugin;
   GMPVideoDecoderCallbackProxy* mCallback;
   GMPVideoHostImpl mVideoHost;
+  const uint32_t mPluginId;
 };
 
 } // namespace gmp
diff --git a/dom/media/gmp/GMPVideoDecoderProxy.h b/dom/media/gmp/GMPVideoDecoderProxy.h
index 1a5c771c988d..5ea089eeb7c1 100644
--- a/dom/media/gmp/GMPVideoDecoderProxy.h
+++ b/dom/media/gmp/GMPVideoDecoderProxy.h
@@ -44,7 +44,7 @@ public:
                           int64_t aRenderTimeMs = -1) = 0;
   virtual nsresult Reset() = 0;
   virtual nsresult Drain() = 0;
-  virtual const uint64_t ParentID() = 0;
+  virtual const uint32_t GetPluginId() const = 0;
 
   // Call to tell GMP/plugin the consumer will no longer use this
   // interface/codec.
diff --git a/dom/media/gmp/GMPVideoEncoderParent.cpp b/dom/media/gmp/GMPVideoEncoderParent.cpp
index 0a0a75bdfc96..92fb88dd5ac0 100644
--- a/dom/media/gmp/GMPVideoEncoderParent.cpp
+++ b/dom/media/gmp/GMPVideoEncoderParent.cpp
@@ -52,7 +52,8 @@ GMPVideoEncoderParent::GMPVideoEncoderParent(GMPContentParent *aPlugin)
   mActorDestroyed(false),
   mPlugin(aPlugin),
   mCallback(nullptr),
-  mVideoHost(this)
+  mVideoHost(this),
+  mPluginId(aPlugin->GetPluginId())
 {
   MOZ_ASSERT(mPlugin);
 
@@ -211,12 +212,6 @@ GMPVideoEncoderParent::SetPeriodicKeyFrames(bool aEnable)
   return GMPNoErr;
 }
 
-const uint32_t
-GMPVideoEncoderParent::ParentID()
-{
-  return mPlugin ? mPlugin->GetPluginId() : 0;
-}
-
 // Note: Consider keeping ActorDestroy sync'd up when making changes here.
 void
 GMPVideoEncoderParent::Shutdown()
diff --git a/dom/media/gmp/GMPVideoEncoderParent.h b/dom/media/gmp/GMPVideoEncoderParent.h
index dcd05cd83284..602daa234243 100644
--- a/dom/media/gmp/GMPVideoEncoderParent.h
+++ b/dom/media/gmp/GMPVideoEncoderParent.h
@@ -45,7 +45,7 @@ public:
   virtual GMPErr SetChannelParameters(uint32_t aPacketLoss, uint32_t aRTT) override;
   virtual GMPErr SetRates(uint32_t aNewBitRate, uint32_t aFrameRate) override;
   virtual GMPErr SetPeriodicKeyFrames(bool aEnable) override;
-  virtual const uint32_t ParentID() override;
+  virtual const uint32_t GetPluginId() const override { return mPluginId; }
 
   // GMPSharedMemManager
   virtual bool Alloc(size_t aSize, Shmem::SharedMemory::SharedMemoryType aType, Shmem* aMem) override
@@ -82,6 +82,7 @@ private:
   GMPVideoEncoderCallbackProxy* mCallback;
   GMPVideoHostImpl mVideoHost;
   nsCOMPtr<nsIThread> mEncodedThread;
+  const uint32_t mPluginId;
 };
 
 } // namespace gmp
diff --git a/dom/media/gmp/GMPVideoEncoderProxy.h b/dom/media/gmp/GMPVideoEncoderProxy.h
index 747aa5d748c1..6990b1b7f965 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 uint32_t ParentID() = 0;
+  virtual const uint32_t GetPluginId() const = 0;
 
   // Call to tell GMP/plugin the consumer will no longer use this
   // interface/codec.
diff --git a/dom/media/gtest/TestGMPCrossOrigin.cpp b/dom/media/gtest/TestGMPCrossOrigin.cpp
index 3a982dec6b1b..27d66f6ff19e 100644
--- a/dom/media/gtest/TestGMPCrossOrigin.cpp
+++ b/dom/media/gtest/TestGMPCrossOrigin.cpp
@@ -174,7 +174,7 @@ private:
       EXPECT_TRUE(aGMP);
       if (aGMP) {
         EXPECT_TRUE(mGMP &&
-                    (mGMP->ParentID() == aGMP->ParentID()) == mShouldBeEqual);
+                    (mGMP->GetPluginId() == aGMP->GetPluginId()) == mShouldBeEqual);
       }
       if (mGMP) {
         mGMP->Close();
diff --git a/media/webrtc/signaling/src/media-conduit/WebrtcGmpVideoCodec.h b/media/webrtc/signaling/src/media-conduit/WebrtcGmpVideoCodec.h
index 7b01a2cc9895..a4f6f8fc1332 100644
--- a/media/webrtc/signaling/src/media-conduit/WebrtcGmpVideoCodec.h
+++ b/media/webrtc/signaling/src/media-conduit/WebrtcGmpVideoCodec.h
@@ -62,7 +62,7 @@ public:
   // Implement VideoEncoder interface.
   virtual const uint64_t PluginID() override
   {
-    return mGMP ? mGMP->ParentID() : mCachedPluginId;
+    return mGMP ? mGMP->GetPluginId() : mCachedPluginId;
   }
 
   virtual void Terminated() override;
@@ -244,7 +244,7 @@ public:
   // Implement VideoDecoder interface.
   virtual const uint64_t PluginID() override
   {
-    return mGMP ? mGMP->ParentID() : mCachedPluginId;
+    return mGMP ? mGMP->GetPluginId() : mCachedPluginId;
   }
 
   virtual void Terminated() override;