--- a/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
@@ -4,17 +4,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "WidevineDecryptor.h"
 
 #include "WidevineAdapter.h"
 #include "WidevineUtils.h"
 #include "WidevineFileIO.h"
 #include "GMPPlatform.h"
-#include <mozilla/SizePrintfMacros.h>
 #include <stdarg.h>
 #include "TimeUnits.h"
 
 using namespace cdm;
 using namespace std;
 
 namespace mozilla {
 
@@ -156,53 +155,16 @@ void
 WidevineDecryptor::SetServerCertificate(uint32_t aPromiseId,
                                         const uint8_t* aServerCert,
                                         uint32_t aServerCertSize)
 {
   CDM_LOG("Decryptor::SetServerCertificate()");
   CDM()->SetServerCertificate(aPromiseId, aServerCert, aServerCertSize);
 }
 
-class WidevineDecryptedBlock : public cdm::DecryptedBlock {
-public:
-
-  WidevineDecryptedBlock()
-    : mBuffer(nullptr)
-    , mTimestamp(0)
-  {
-  }
-
-  ~WidevineDecryptedBlock() override {
-    if (mBuffer) {
-      mBuffer->Destroy();
-      mBuffer = nullptr;
-    }
-  }
-
-  void SetDecryptedBuffer(cdm::Buffer* aBuffer) override {
-    mBuffer = aBuffer;
-  }
-
-  cdm::Buffer* DecryptedBuffer() override {
-    return mBuffer;
-  }
-
-  void SetTimestamp(int64_t aTimestamp) override {
-    mTimestamp = aTimestamp;
-  }
-
-  int64_t Timestamp() const override {
-    return mTimestamp;
-  }
-
-private:
-  cdm::Buffer* mBuffer;
-  int64_t mTimestamp;
-};
-
 cdm::Time
 WidevineDecryptor::ThrottleDecrypt(cdm::Time aWallTime, cdm::Time aSampleDuration)
 {
   const cdm::Time WindowSize = 1.0;
   const cdm::Time MaxThroughput = 2.0;
 
   // Forget decrypts that happened before the start of our window.
   while (!mDecrypts.empty() && mDecrypts.front().mWallTime < aWallTime - WindowSize) {
@@ -322,38 +284,16 @@ WidevineDecryptor::DecryptingComplete()
   // WidevineVideoDecoder, or a runnable), the CDMWrapper destroys
   // the CDM.
   mCDM = nullptr;
   sDecryptors.erase(mInstanceId);
   mCallback = nullptr;
   Release();
 }
 
-class WidevineBuffer : public cdm::Buffer {
-public:
-  explicit WidevineBuffer(size_t aSize) {
-    CDM_LOG("WidevineBuffer(size=%" PRIuSIZE ") created", aSize);
-    mBuffer.SetLength(aSize);
-  }
-  ~WidevineBuffer() override {
-    CDM_LOG("WidevineBuffer(size=%" PRIu32 ") destroyed", Size());
-  }
-  void Destroy() override { delete this; }
-  uint32_t Capacity() const override { return mBuffer.Length(); };
-  uint8_t* Data() override { return mBuffer.Elements(); }
-  void SetSize(uint32_t aSize) override { mBuffer.SetLength(aSize); }
-  uint32_t Size() const override { return mBuffer.Length(); }
-
-private:
-  WidevineBuffer(const WidevineBuffer&);
-  void operator=(const WidevineBuffer&);
-
-  nsTArray<uint8_t> mBuffer;
-};
-
 Buffer*
 WidevineDecryptor::Allocate(uint32_t aCapacity)
 {
   CDM_LOG("Decryptor::Allocate(capacity=%u)", aCapacity);
   return new WidevineBuffer(aCapacity);
 }
 
 class TimerTask : public GMPTask {

--- a/dom/media/gmp/widevine-adapter/WidevineUtils.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineUtils.cpp
@@ -1,19 +1,21 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "WidevineUtils.h"
 #include "WidevineDecryptor.h"
+#include <mozilla/SizePrintfMacros.h>
 
 #include "gmp-api/gmp-errors.h"
 #include <stdarg.h>
 #include <stdio.h>
+#include <inttypes.h>
 
 namespace mozilla {
 
 namespace detail {
 LogModule* GetCDMLog()
 {
   static LazyLogModule sLog("CDM");
   return sLog;
@@ -71,9 +73,95 @@ CDMWrapper::CDMWrapper(cdm::ContentDecry
 
 CDMWrapper::~CDMWrapper()
 {
   CDM_LOG("CDMWrapper destroying CDM=%p", mCDM);
   mCDM->Destroy();
   mCDM = nullptr;
 }
 
+WidevineBuffer::WidevineBuffer(size_t aSize)
+{
+  CDM_LOG("WidevineBuffer(size=%" PRIuSIZE ") created", aSize);
+  mBuffer.SetLength(aSize);
+}
+
+WidevineBuffer::~WidevineBuffer()
+{
+  CDM_LOG("WidevineBuffer(size=%" PRIu32 ") destroyed", Size());
+}
+
+void
+WidevineBuffer::Destroy()
+{
+  delete this;
+}
+
+uint32_t
+WidevineBuffer::Capacity() const
+{
+  return mBuffer.Length();
+}
+
+uint8_t*
+WidevineBuffer::Data()
+{
+  return mBuffer.Elements();
+}
+
+void
+WidevineBuffer::SetSize(uint32_t aSize)
+{
+  mBuffer.SetLength(aSize);
+}
+
+uint32_t
+WidevineBuffer::Size() const
+{
+  return mBuffer.Length();
+}
+
+nsTArray<uint8_t>
+WidevineBuffer::ExtractBuffer() {
+  nsTArray<uint8_t> out;
+  out.SwapElements(mBuffer);
+  return out;
+}
+
+WidevineDecryptedBlock::WidevineDecryptedBlock()
+  : mBuffer(nullptr)
+  , mTimestamp(0)
+{
+}
+
+WidevineDecryptedBlock::~WidevineDecryptedBlock()
+{
+  if (mBuffer) {
+    mBuffer->Destroy();
+    mBuffer = nullptr;
+  }
+}
+
+void
+WidevineDecryptedBlock::SetDecryptedBuffer(cdm::Buffer* aBuffer)
+{
+  mBuffer = aBuffer;
+}
+
+cdm::Buffer*
+WidevineDecryptedBlock::DecryptedBuffer()
+{
+  return mBuffer;
+}
+
+void
+WidevineDecryptedBlock::SetTimestamp(int64_t aTimestamp)
+{
+  mTimestamp = aTimestamp;
+}
+
+int64_t
+WidevineDecryptedBlock::Timestamp() const
+{
+  return mTimestamp;
+}
+
 } // namespace mozilla

--- a/dom/media/gmp/widevine-adapter/WidevineUtils.h
+++ b/dom/media/gmp/widevine-adapter/WidevineUtils.h
@@ -56,11 +56,48 @@ private:
 
 void InitInputBuffer(const GMPEncryptedBufferMetadata* aCrypto,
                      int64_t aTimestamp,
                      const uint8_t* aData,
                      size_t aDataSize,
                      cdm::InputBuffer &aInputBuffer,
                      nsTArray<cdm::SubsampleEntry> &aSubsamples);
 
+class WidevineBuffer : public cdm::Buffer
+{
+public:
+  explicit WidevineBuffer(size_t aSize);
+  ~WidevineBuffer() override;
+  void Destroy() override;
+  uint32_t Capacity() const override;
+  uint8_t* Data() override;
+  void SetSize(uint32_t aSize) override;
+  uint32_t Size() const override;
+
+  // Moves contents of buffer out into temporary.
+  // Note: This empties the buffer.
+  nsTArray<uint8_t> ExtractBuffer();
+
+private:
+  nsTArray<uint8_t> mBuffer;
+  WidevineBuffer(const WidevineBuffer&);
+  void operator=(const WidevineBuffer&);
+};
+
+class WidevineDecryptedBlock : public cdm::DecryptedBlock
+{
+public:
+
+  WidevineDecryptedBlock();
+  ~WidevineDecryptedBlock() override;
+  void SetDecryptedBuffer(cdm::Buffer* aBuffer) override;
+  cdm::Buffer* DecryptedBuffer() override;
+  void SetTimestamp(int64_t aTimestamp) override;
+  int64_t Timestamp() const override;
+
+private:
+  cdm::Buffer* mBuffer;
+  int64_t mTimestamp;
+};
+
 } // namespace mozilla
 
 #endif // WidevineUtils_h_

--- a/dom/media/gmp/widevine-adapter/moz.build
+++ b/dom/media/gmp/widevine-adapter/moz.build
@@ -9,16 +9,21 @@ SOURCES += [
     'WidevineDecryptor.cpp',
     'WidevineDummyDecoder.cpp',
     'WidevineFileIO.cpp',
     'WidevineUtils.cpp',
     'WidevineVideoDecoder.cpp',
     'WidevineVideoFrame.cpp',
 ]
 
+EXPORTS += [
+    'WidevineDecryptor.h',
+    'WidevineUtils.h'
+]
+
 FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
     '/dom/media/gmp',
 ]
 
 if CONFIG['CLANG_CXX']:
     CXXFLAGS += ['-Wno-error=shadow']