diff --git a/dom/media/AudioStream.h b/dom/media/AudioStream.h
index dc84feaf63bd..f9dce5fb6a6a 100644
--- a/dom/media/AudioStream.h
+++ b/dom/media/AudioStream.h
@@ -88,7 +88,7 @@ public:
   void SetCapacity(uint32_t aCapacity) {
     MOZ_ASSERT(!mBuffer, "Buffer allocated.");
     mCapacity = aCapacity;
-    mBuffer = new uint8_t[mCapacity];
+    mBuffer = MakeUnique<uint8_t[]>(mCapacity);
   }
 
   uint32_t Length() {
@@ -137,12 +137,12 @@ public:
   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
   {
     size_t amount = 0;
-    amount += mBuffer.SizeOfExcludingThis(aMallocSizeOf);
+    amount += aMallocSizeOf(mBuffer.get());
     return amount;
   }
 
 private:
-  nsAutoArrayPtr<uint8_t> mBuffer;
+  UniquePtr<uint8_t[]> mBuffer;
   uint32_t mCapacity;
   uint32_t mStart;
   uint32_t mCount;
diff --git a/dom/media/FileBlockCache.h b/dom/media/FileBlockCache.h
index e16fa7592fa0..a32bfb638a2d 100644
--- a/dom/media/FileBlockCache.h
+++ b/dom/media/FileBlockCache.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/Attributes.h"
 #include "mozilla/Monitor.h"
+#include "mozilla/UniquePtr.h"
 #include "nsTArray.h"
 #include "MediaCache.h"
 #include "nsDeque.h"
@@ -96,7 +97,7 @@ public:
     explicit BlockChange(const uint8_t* aData)
       : mSourceBlockIndex(-1)
     {
-      mData = new uint8_t[BLOCK_SIZE];
+      mData = MakeUnique<uint8_t[]>(BLOCK_SIZE);
       memcpy(mData.get(), aData, BLOCK_SIZE);
     }
 
@@ -105,7 +106,7 @@ public:
     explicit BlockChange(int32_t aSourceBlockIndex)
       : mSourceBlockIndex(aSourceBlockIndex) {}
 
-    nsAutoArrayPtr<uint8_t> mData;
+    UniquePtr<uint8_t[]> mData;
     const int32_t mSourceBlockIndex;
 
     bool IsMove() const {
diff --git a/dom/media/MediaCache.cpp b/dom/media/MediaCache.cpp
index e42a236f8cd5..a9c76e7621b5 100644
--- a/dom/media/MediaCache.cpp
+++ b/dom/media/MediaCache.cpp
@@ -379,7 +379,7 @@ MediaCacheStream::MediaCacheStream(ChannelMediaResource* aClient)
     mPinCount(0),
     mCurrentMode(MODE_PLAYBACK),
     mMetadataInPartialBlockBuffer(false),
-    mPartialBlockBuffer(new int64_t[BLOCK_SIZE/sizeof(int64_t)])
+    mPartialBlockBuffer(MakeUnique<int64_t[]>(BLOCK_SIZE/sizeof(int64_t)))
 {
 }
 
@@ -393,7 +393,7 @@ size_t MediaCacheStream::SizeOfExcludingThis(
   size += mReadaheadBlocks.SizeOfExcludingThis(aMallocSizeOf);
   size += mMetadataBlocks.SizeOfExcludingThis(aMallocSizeOf);
   size += mPlayedBlocks.SizeOfExcludingThis(aMallocSizeOf);
-  size += mPartialBlockBuffer.SizeOfExcludingThis(aMallocSizeOf);
+  size += aMallocSizeOf(mPartialBlockBuffer.get());
 
   return size;
 }
@@ -1842,7 +1842,7 @@ MediaCacheStream::FlushPartialBlockInternal(bool aNotifyAll,
     // Write back the partial block
     memset(reinterpret_cast<char*>(mPartialBlockBuffer.get()) + blockOffset, 0,
            BLOCK_SIZE - blockOffset);
-    gMediaCache->AllocateAndWriteBlock(this, mPartialBlockBuffer,
+    gMediaCache->AllocateAndWriteBlock(this, mPartialBlockBuffer.get(),
         mMetadataInPartialBlockBuffer ? MODE_METADATA : MODE_PLAYBACK);
   }
 
diff --git a/dom/media/MediaCache.h b/dom/media/MediaCache.h
index 0c49986f39e8..68a82f1caf78 100644
--- a/dom/media/MediaCache.h
+++ b/dom/media/MediaCache.h
@@ -12,6 +12,7 @@
 #include "nsHashKeys.h"
 #include "nsTHashtable.h"
 #include "Intervals.h"
+#include "mozilla/UniquePtr.h"
 
 class nsIPrincipal;
 
@@ -510,7 +511,7 @@ private:
   // Use int64_t so that the data is well-aligned.
   // Heap allocate this buffer since the exact power-of-2 will cause allocation
   // slop when combined with the rest of the object members.
-  nsAutoArrayPtr<int64_t> mPartialBlockBuffer;
+  UniquePtr<int64_t[]> mPartialBlockBuffer;
 };
 
 } // namespace mozilla
diff --git a/dom/media/MediaData.cpp b/dom/media/MediaData.cpp
index 9635190f6e26..d2f9cc06e283 100644
--- a/dom/media/MediaData.cpp
+++ b/dom/media/MediaData.cpp
@@ -12,6 +12,7 @@
 #endif
 #include "VideoUtils.h"
 #include "ImageContainer.h"
+#include "mozilla/UniquePtrExtensions.h"
 
 #ifdef MOZ_WIDGET_GONK
 #include <cutils/properties.h>
@@ -533,8 +534,7 @@ MediaRawData::EnsureCapacity(size_t aSize)
   if (mData && mCapacity >= sizeNeeded) {
     return true;
   }
-  nsAutoArrayPtr<uint8_t> newBuffer;
-  newBuffer = new (fallible) uint8_t[sizeNeeded];
+  auto newBuffer = MakeUniqueFallible<uint8_t[]>(sizeNeeded);
   if (!newBuffer) {
     return false;
   }
@@ -546,7 +546,7 @@ MediaRawData::EnsureCapacity(size_t aSize)
   MOZ_ASSERT(uintptr_t(newData) % (RAW_DATA_ALIGNMENT+1) == 0);
   memcpy(newData, mData, mSize);
 
-  mBuffer = newBuffer.forget();
+  mBuffer = Move(newBuffer);
   mCapacity = sizeNeeded;
   mData = newData;
 
diff --git a/dom/media/MediaData.h b/dom/media/MediaData.h
index 6dc4f2ef61d7..50f67418494a 100644
--- a/dom/media/MediaData.h
+++ b/dom/media/MediaData.h
@@ -425,7 +425,7 @@ private:
   bool EnsureCapacity(size_t aSize);
   uint8_t* mData;
   size_t mSize;
-  nsAutoArrayPtr<uint8_t> mBuffer;
+  UniquePtr<uint8_t[]> mBuffer;
   uint32_t mCapacity;
   CryptoSample mCryptoInternal;
   MediaRawData(const MediaRawData&); // Not implemented
diff --git a/dom/media/RtspMediaResource.cpp b/dom/media/RtspMediaResource.cpp
index 0c6eddae9d34..18f48f2262e6 100644
--- a/dom/media/RtspMediaResource.cpp
+++ b/dom/media/RtspMediaResource.cpp
@@ -12,6 +12,7 @@
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/UniquePtr.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsIStreamingProtocolService.h"
 #include "nsServiceManagerUtils.h"
@@ -72,7 +73,7 @@ public:
     MOZ_COUNT_CTOR(RtspTrackBuffer);
     mTrackIdx = aTrackIdx;
     MOZ_ASSERT(mSlotSize < UINT32_MAX / BUFFER_SLOT_NUM);
-    mRingBuffer = new uint8_t[mTotalBufferSize];
+    mRingBuffer = MakeUnique<uint8_t[]>(mTotalBufferSize);
     Reset();
   };
   ~RtspTrackBuffer() {
@@ -85,7 +86,7 @@ public:
     size_t size = aMallocSizeOf(this);
 
     // excluding this
-    size += mRingBuffer.SizeOfExcludingThis(aMallocSizeOf);
+    size += aMallocSizeOf(mRingBuffer.get());
 
     return size;
   }
@@ -179,7 +180,7 @@ private:
   BufferSlotData mBufferSlotData[BUFFER_SLOT_NUM];
 
   // The ring buffer pointer.
-  nsAutoArrayPtr<uint8_t> mRingBuffer;
+  UniquePtr<uint8_t[]> mRingBuffer;
   // Each slot's size.
   uint32_t mSlotSize;
   // Total mRingBuffer's total size.
diff --git a/dom/media/VideoSegment.cpp b/dom/media/VideoSegment.cpp
index 1d97cefa75ca..551ecf7a9ca6 100644
--- a/dom/media/VideoSegment.cpp
+++ b/dom/media/VideoSegment.cpp
@@ -68,7 +68,7 @@ VideoFrame::CreateBlackImage(const gfx::IntSize& aSize)
   data.mYSize = gfx::IntSize(aSize.width, aSize.height);
   data.mYStride = (int32_t) (aSize.width * lumaBpp / 8.0);
   data.mCbCrStride = (int32_t) (aSize.width * chromaBpp / 8.0);
-  data.mCbChannel = frame.rwget() + aSize.height * data.mYStride;
+  data.mCbChannel = frame.get() + aSize.height * data.mYStride;
   data.mCrChannel = data.mCbChannel + aSize.height * data.mCbCrStride / 2;
   data.mCbCrSize = gfx::IntSize(aSize.width / 2, aSize.height / 2);
   data.mPicX = 0;
diff --git a/dom/media/android/AndroidMediaResourceServer.cpp b/dom/media/android/AndroidMediaResourceServer.cpp
index dd4f0a70f671..209844c0e82b 100644
--- a/dom/media/android/AndroidMediaResourceServer.cpp
+++ b/dom/media/android/AndroidMediaResourceServer.cpp
@@ -6,6 +6,7 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/Base64.h"
 #include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/UniquePtr.h"
 #include "nsThreadUtils.h"
 #include "nsIServiceManager.h"
 #include "nsISocketTransport.h"
@@ -263,7 +264,7 @@ ServeResourceEvent::Run() {
   // HTTP response headers sent below. A static_assert ensures
   // this where the buffer is used.
   const int buffer_size = 32768;
-  nsAutoArrayPtr<char> b(new char[buffer_size]);
+  auto b = MakeUnique<char[]>(buffer_size);
 
   // If we know the length of the resource, send a Content-Length header.
   int64_t contentlength = resource->GetLength() - start;
@@ -271,8 +272,8 @@ ServeResourceEvent::Run() {
     static_assert (buffer_size > 1024,
                    "buffer_size must be large enough "
                    "to hold response headers");
-    snprintf(b, buffer_size, "Content-Length: %" PRId64 "\r\n", contentlength);
-    rv = WriteAll(b, strlen(b));
+    snprintf(b.get(), buffer_size, "Content-Length: %" PRId64 "\r\n", contentlength);
+    rv = WriteAll(b.get(), strlen(b.get()));
     if (NS_FAILED(rv)) { Shutdown(); return NS_OK; }
   }
 
@@ -282,10 +283,10 @@ ServeResourceEvent::Run() {
     static_assert (buffer_size > 1024,
                    "buffer_size must be large enough "
                    "to hold response headers");
-    snprintf(b, buffer_size, "Content-Range: "
+    snprintf(b.get(), buffer_size, "Content-Range: "
              "bytes %" PRId64 "-%" PRId64 "/%" PRId64 "\r\n",
              start, resource->GetLength() - 1, resource->GetLength());
-    rv = WriteAll(b, strlen(b));
+    rv = WriteAll(b.get(), strlen(b.get()));
     if (NS_FAILED(rv)) { Shutdown(); return NS_OK; }
   }
 
@@ -297,7 +298,7 @@ ServeResourceEvent::Run() {
 
   // Read data from media resource
   uint32_t bytesRead = 0; // Number of bytes read/written to streams
-  rv = resource->ReadAt(start, b, buffer_size, &bytesRead);
+  rv = resource->ReadAt(start, b.get(), buffer_size, &bytesRead);
   while (NS_SUCCEEDED(rv) && bytesRead != 0) {
     // Keep track of what we think the starting position for the next read
     // is. This is used in subsequent ReadAt calls to ensure we are reading
@@ -306,10 +307,10 @@ ServeResourceEvent::Run() {
     start += bytesRead;
 
     // Write data obtained from media resource to output stream
-    rv = WriteAll(b, bytesRead);
+    rv = WriteAll(b.get(), bytesRead);
     if (NS_FAILED (rv)) break;
 
-    rv = resource->ReadAt(start, b, 32768, &bytesRead);
+    rv = resource->ReadAt(start, b.get(), 32768, &bytesRead);
   }
 
   Shutdown();
diff --git a/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.cpp b/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.cpp
index 79ad83caae21..cf3f36b40377 100644
--- a/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.cpp
+++ b/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.cpp
@@ -127,7 +127,7 @@ TrackRunBox::fillSampleTable()
     return 0;
   }
   uint32_t len = frames.Length();
-  sample_info_table = new tbl[len];
+  sample_info_table = MakeUnique<tbl[]>(len);
   // Create sample table according to 14496-12 8.8.8.2.
   for (uint32_t i = 0; i < len; i++) {
     // Sample size.
diff --git a/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.h b/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.h
index 635f7b6d3101..a6dc1b0468d4 100644
--- a/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.h
+++ b/dom/media/encoder/fmp4_muxer/ISOMediaBoxes.h
@@ -11,6 +11,7 @@
 #include "nsTArray.h"
 #include "nsAutoPtr.h"
 #include "MuxerOperation.h"
+#include "mozilla/UniquePtr.h"
 
 #define WRITE_FULLBOX(_compositor, _size)       \
   BoxSizeChecker checker(_compositor, _size);   \
@@ -262,7 +263,7 @@ public:
   // the following are optional fields
   uint32_t data_offset; // data offset exists when audio/video are present in file.
   uint32_t first_sample_flags;
-  nsAutoArrayPtr<tbl> sample_info_table;
+  UniquePtr<tbl[]> sample_info_table;
 
   // MuxerOperation methods
   nsresult Generate(uint32_t* aBoxSize) override;
@@ -404,7 +405,7 @@ public:
   } tbl;
 
   uint32_t entry_count;
-  nsAutoArrayPtr<tbl> sample_tbl;
+  UniquePtr<tbl[]> sample_tbl;
 
   // MuxerOperation methods
   nsresult Generate(uint32_t* aBoxSize) override;
@@ -430,7 +431,7 @@ public:
   } tbl;
 
   uint32_t entry_count;
-  nsAutoArrayPtr<tbl> sample_tbl;
+  UniquePtr<tbl[]> sample_tbl;
 
   // MuxerOperation methods
   nsresult Generate(uint32_t* aBoxSize) override;
@@ -455,7 +456,7 @@ public:
   } tbl;
 
   uint32_t entry_count;
-  nsAutoArrayPtr<tbl> sample_tbl;
+  UniquePtr<tbl[]> sample_tbl;
 
   // MuxerOperation methods
   nsresult Generate(uint32_t* aBoxSize) override;
diff --git a/dom/media/fmp4/MP4Stream.cpp b/dom/media/fmp4/MP4Stream.cpp
index 20c0c6af8b2a..615a7dc01529 100644
--- a/dom/media/fmp4/MP4Stream.cpp
+++ b/dom/media/fmp4/MP4Stream.cpp
@@ -44,7 +44,7 @@ MP4Stream::BlockingReadIntoCache(int64_t aOffset, size_t aCount, Monitor* aToUnl
   MOZ_ASSERT(block.mCount >= bytesRead);
   block.mCount = bytesRead;
 
-  mCache.AppendElement(block);
+  mCache.AppendElement(Move(block));
   return true;
 }
 
diff --git a/dom/media/fmp4/MP4Stream.h b/dom/media/fmp4/MP4Stream.h
index b5d0f562a889..22a7faf89acd 100644
--- a/dom/media/fmp4/MP4Stream.h
+++ b/dom/media/fmp4/MP4Stream.h
@@ -13,6 +13,7 @@
 
 #include "mozilla/Maybe.h"
 #include "mozilla/Monitor.h"
+#include "mozilla/UniquePtrExtensions.h"
 
 namespace mozilla {
 
@@ -74,9 +75,15 @@ private:
     int64_t mOffset;
     size_t mCount;
 
+    CacheBlock(CacheBlock&& aOther)
+      : mOffset(aOther.mOffset)
+      , mCount(aOther.mCount)
+      , mBuffer(Move(aOther.mBuffer))
+    {}
+
     bool Init()
     {
-      mBuffer = new (fallible) char[mCount];
+      mBuffer = MakeUniqueFallible<char[]>(mCount);
       return !!mBuffer;
     }
 
@@ -87,7 +94,10 @@ private:
     }
 
   private:
-    nsAutoArrayPtr<char> mBuffer;
+    CacheBlock(const CacheBlock&) = delete;
+    CacheBlock& operator=(const CacheBlock&) = delete;
+
+    UniquePtr<char[]> mBuffer;
   };
   nsTArray<CacheBlock> mCache;
 };
diff --git a/dom/media/gmp/GMPLoader.cpp b/dom/media/gmp/GMPLoader.cpp
index 99282ba23634..c6a93a7a4c94 100644
--- a/dom/media/gmp/GMPLoader.cpp
+++ b/dom/media/gmp/GMPLoader.cpp
@@ -7,6 +7,7 @@
 #include "GMPLoader.h"
 #include <stdio.h>
 #include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
 #include "gmp-entrypoints.h"
 #include "prlink.h"
 #include "prenv.h"
@@ -247,12 +248,12 @@ GMPLoaderImpl::Load(const char* aUTF8LibPath,
     return false;
   }
 
-  nsAutoArrayPtr<wchar_t> widePath(new wchar_t[pathLen]);
-  if (MultiByteToWideChar(CP_UTF8, 0, aUTF8LibPath, -1, widePath, pathLen) == 0) {
+  auto widePath = MakeUnique<wchar_t[]>(pathLen);
+  if (MultiByteToWideChar(CP_UTF8, 0, aUTF8LibPath, -1, widePath.get(), pathLen) == 0) {
     return false;
   }
 
-  libSpec.value.pathname_u = widePath;
+  libSpec.value.pathname_u = widePath.get();
   libSpec.type = PR_LibSpec_PathnameU;
 #else
   libSpec.value.pathname = aUTF8LibPath;
diff --git a/dom/media/platforms/agnostic/BlankDecoderModule.cpp b/dom/media/platforms/agnostic/BlankDecoderModule.cpp
index 51323ec2506f..ed5d0d13ae3e 100644
--- a/dom/media/platforms/agnostic/BlankDecoderModule.cpp
+++ b/dom/media/platforms/agnostic/BlankDecoderModule.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/mozalloc.h" // for operator new, and new (fallible)
 #include "mozilla/RefPtr.h"
 #include "mozilla/TaskQueue.h"
+#include "mozilla/UniquePtr.h"
 #include "nsRect.h"
 #include "PlatformDecoderModule.h"
 #include "TimeUnits.h"
@@ -118,12 +119,12 @@ public:
     // with a U and V plane that are half the size of the Y plane, i.e 8 bit,
     // 2x2 subsampled. Have the data pointers of each frame point to the
     // first plane, they'll always be zero'd memory anyway.
-    nsAutoArrayPtr<uint8_t> frame(new uint8_t[mFrameWidth * mFrameHeight]);
-    memset(frame, 0, mFrameWidth * mFrameHeight);
+    auto frame = MakeUnique<uint8_t[]>(mFrameWidth * mFrameHeight);
+    memset(frame.get(), 0, mFrameWidth * mFrameHeight);
     VideoData::YCbCrBuffer buffer;
 
     // Y plane.
-    buffer.mPlanes[0].mData = frame;
+    buffer.mPlanes[0].mData = frame.get();
     buffer.mPlanes[0].mStride = mFrameWidth;
     buffer.mPlanes[0].mHeight = mFrameHeight;
     buffer.mPlanes[0].mWidth = mFrameWidth;
@@ -131,7 +132,7 @@ public:
     buffer.mPlanes[0].mSkip = 0;
 
     // Cb plane.
-    buffer.mPlanes[1].mData = frame;
+    buffer.mPlanes[1].mData = frame.get();
     buffer.mPlanes[1].mStride = mFrameWidth / 2;
     buffer.mPlanes[1].mHeight = mFrameHeight / 2;
     buffer.mPlanes[1].mWidth = mFrameWidth / 2;
@@ -139,7 +140,7 @@ public:
     buffer.mPlanes[1].mSkip = 0;
 
     // Cr plane.
-    buffer.mPlanes[2].mData = frame;
+    buffer.mPlanes[2].mData = frame.get();
     buffer.mPlanes[2].mStride = mFrameWidth / 2;
     buffer.mPlanes[2].mHeight = mFrameHeight / 2;
     buffer.mPlanes[2].mWidth = mFrameWidth / 2;
diff --git a/dom/media/platforms/apple/AppleATDecoder.cpp b/dom/media/platforms/apple/AppleATDecoder.cpp
index fd8078208d67..1257af507d44 100644
--- a/dom/media/platforms/apple/AppleATDecoder.cpp
+++ b/dom/media/platforms/apple/AppleATDecoder.cpp
@@ -10,6 +10,7 @@
 #include "MediaInfo.h"
 #include "AppleATDecoder.h"
 #include "mozilla/Logging.h"
+#include "mozilla/UniquePtr.h"
 
 extern mozilla::LogModule* GetPDMLog();
 #define LOG(...) MOZ_LOG(GetPDMLog(), mozilla::LogLevel::Debug, (__VA_ARGS__))
@@ -211,8 +212,7 @@ AppleATDecoder::DecodeSample(MediaRawData* aSample)
   const uint32_t maxDecodedSamples = MAX_AUDIO_FRAMES * channels;
 
   // Descriptions for _decompressed_ audio packets. ignored.
-  nsAutoArrayPtr<AudioStreamPacketDescription>
-    packets(new AudioStreamPacketDescription[MAX_AUDIO_FRAMES]);
+  auto packets = MakeUnique<AudioStreamPacketDescription[]>(MAX_AUDIO_FRAMES);
 
   // This API insists on having packets spoon-fed to it from a callback.
   // This structure exists only to pass our state.
@@ -220,7 +220,7 @@ AppleATDecoder::DecodeSample(MediaRawData* aSample)
     { channels, (UInt32)aSample->Size(), aSample->Data() };
 
   // Decompressed audio buffer
-  nsAutoArrayPtr<AudioDataValue> decoded(new AudioDataValue[maxDecodedSamples]);
+  auto decoded = MakeUnique<AudioDataValue[]>(maxDecodedSamples);
 
   do {
     AudioBufferList decBuffer;
@@ -328,14 +328,13 @@ AppleATDecoder::GetInputAudioDescription(AudioStreamBasicDescription& aDesc,
     return NS_OK;
   }
   size_t listCount = formatListSize / sizeof(AudioFormatListItem);
-  nsAutoArrayPtr<AudioFormatListItem> formatList(
-    new AudioFormatListItem[listCount]);
+  auto formatList = MakeUnique<AudioFormatListItem[]>(listCount);
 
   rv = AudioFormatGetProperty(kAudioFormatProperty_FormatList,
                               sizeof(formatInfo),
                               &formatInfo,
                               &formatListSize,
-                              formatList);
+                              formatList.get());
   if (rv) {
     return NS_OK;
   }
@@ -348,7 +347,7 @@ AppleATDecoder::GetInputAudioDescription(AudioStreamBasicDescription& aDesc,
   UInt32 indexSize = sizeof(itemIndex);
   rv = AudioFormatGetProperty(kAudioFormatProperty_FirstPlayableFormatFromList,
                               formatListSize,
-                              formatList,
+                              formatList.get(),
                               &indexSize,
                               &itemIndex);
   if (rv) {
@@ -438,9 +437,9 @@ _MetadataCallback(void* aAppleATDecoder,
       decoder->mFileStreamError = true;
       return;
     }
-    nsAutoArrayPtr<uint8_t> data(new uint8_t[size]);
+    auto data = MakeUnique<uint8_t[]>(size);
     rv = AudioFileStreamGetProperty(aStream, aProperty,
-                                    &size, data);
+                                    &size, data.get());
     if (rv) {
       LOG("Couldn't get property '%s' (%s)",
           FourCC2Str(aProperty), FourCC2Str(rv));
diff --git a/dom/media/platforms/gonk/GonkVideoDecoderManager.cpp b/dom/media/platforms/gonk/GonkVideoDecoderManager.cpp
index 43e1a479b4d2..60e5fc558552 100644
--- a/dom/media/platforms/gonk/GonkVideoDecoderManager.cpp
+++ b/dom/media/platforms/gonk/GonkVideoDecoderManager.cpp
@@ -669,8 +669,7 @@ GonkVideoDecoderManager::GetColorConverterBuffer(int32_t aWidth, int32_t aHeight
   size_t yuv420p_v_size = yuv420p_u_size;
   size_t yuv420p_size = yuv420p_y_size + yuv420p_u_size + yuv420p_v_size;
   if (mColorConverterBufferSize != yuv420p_size) {
-    mColorConverterBuffer = nullptr; // release the previous buffer first
-    mColorConverterBuffer = new uint8_t[yuv420p_size];
+    mColorConverterBuffer = MakeUnique<uint8_t[]>(yuv420p_size);
     mColorConverterBufferSize = yuv420p_size;
   }
   return mColorConverterBuffer.get();
diff --git a/dom/media/platforms/gonk/GonkVideoDecoderManager.h b/dom/media/platforms/gonk/GonkVideoDecoderManager.h
index 496b6f5da0ca..1e3b3139b6ba 100644
--- a/dom/media/platforms/gonk/GonkVideoDecoderManager.h
+++ b/dom/media/platforms/gonk/GonkVideoDecoderManager.h
@@ -15,6 +15,7 @@
 #include "GonkNativeWindow.h"
 #include "GonkNativeWindowClient.h"
 #include "mozilla/layers/FenceUtils.h"
+#include "mozilla/UniquePtr.h"
 #include <ui/Fence.h>
 
 using namespace android;
@@ -112,7 +113,7 @@ private:
 
   // color converter
   android::I420ColorConverterHelper mColorConverter;
-  nsAutoArrayPtr<uint8_t> mColorConverterBuffer;
+  UniquePtr<uint8_t[]> mColorConverterBuffer;
   size_t mColorConverterBufferSize;
 
   android::sp<android::GonkNativeWindow> mNativeWindow;
diff --git a/dom/media/raw/RawReader.cpp b/dom/media/raw/RawReader.cpp
index 1185cfc598e9..cfe775c1a9cd 100644
--- a/dom/media/raw/RawReader.cpp
+++ b/dom/media/raw/RawReader.cpp
@@ -10,6 +10,7 @@
 #include "VideoUtils.h"
 #include "nsISeekableStream.h"
 #include "gfx2DGlue.h"
+#include "mozilla/UniquePtr.h"
 
 using namespace mozilla;
 using namespace mozilla::media;
@@ -138,7 +139,7 @@ bool RawReader::DecodeVideoFrame(bool &aKeyframeSkip,
   int64_t currentFrameTime = USECS_PER_S * mCurrentFrame / mFrameRate;
   uint32_t length = mFrameSize - sizeof(RawPacketHeader);
 
-  nsAutoArrayPtr<uint8_t> buffer(new uint8_t[length]);
+  auto buffer = MakeUnique<uint8_t[]>(length);
 
   // We're always decoding one frame when called
   while(true) {
@@ -151,7 +152,7 @@ bool RawReader::DecodeVideoFrame(bool &aKeyframeSkip,
       return false;
     }
 
-    if (!ReadFromResource(buffer, length)) {
+    if (!ReadFromResource(buffer.get(), length)) {
       return false;
     }
 
@@ -165,7 +166,7 @@ bool RawReader::DecodeVideoFrame(bool &aKeyframeSkip,
   }
 
   VideoData::YCbCrBuffer b;
-  b.mPlanes[0].mData = buffer;
+  b.mPlanes[0].mData = buffer.get();
   b.mPlanes[0].mStride = mMetadata.frameWidth * mMetadata.lumaChannelBpp / 8.0;
   b.mPlanes[0].mHeight = mMetadata.frameHeight;
   b.mPlanes[0].mWidth = mMetadata.frameWidth;
@@ -173,7 +174,7 @@ bool RawReader::DecodeVideoFrame(bool &aKeyframeSkip,
 
   uint32_t cbcrStride = mMetadata.frameWidth * mMetadata.chromaChannelBpp / 8.0;
 
-  b.mPlanes[1].mData = buffer + mMetadata.frameHeight * b.mPlanes[0].mStride;
+  b.mPlanes[1].mData = buffer.get() + mMetadata.frameHeight * b.mPlanes[0].mStride;
   b.mPlanes[1].mStride = cbcrStride;
   b.mPlanes[1].mHeight = mMetadata.frameHeight / 2;
   b.mPlanes[1].mWidth = mMetadata.frameWidth / 2;
diff --git a/dom/media/wave/WaveReader.cpp b/dom/media/wave/WaveReader.cpp
index bb58fc41d5d8..3c53e3e6901b 100644
--- a/dom/media/wave/WaveReader.cpp
+++ b/dom/media/wave/WaveReader.cpp
@@ -14,6 +14,7 @@
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/CheckedInt.h"
 #include "mozilla/Endian.h"
+#include "mozilla/UniquePtr.h"
 #include <algorithm>
 
 using namespace mozilla::media;
@@ -191,9 +192,9 @@ bool WaveReader::DecodeAudioData()
 
   static_assert(uint64_t(BLOCK_SIZE) < UINT_MAX / sizeof(char),
                 "BLOCK_SIZE too large for enumerator.");
-  nsAutoArrayPtr<char> dataBuffer(new char[static_cast<size_t>(readSize)]);
+  auto dataBuffer = MakeUnique<char[]>(static_cast<size_t>(readSize));
 
-  if (!ReadAll(dataBuffer, readSize)) {
+  if (!ReadAll(dataBuffer.get(), readSize)) {
     return false;
   }
 
@@ -406,7 +407,7 @@ WaveReader::LoadFormatChunk(uint32_t aChunkSize)
     if (extra > 0) {
       static_assert(UINT16_MAX + (UINT16_MAX % 2) < UINT_MAX / sizeof(char),
                     "chunkExtension array too large for iterator.");
-      nsAutoArrayPtr<char> chunkExtension(new char[extra]);
+      auto chunkExtension = MakeUnique<char[]>(extra);
       if (!ReadAll(chunkExtension.get(), extra)) {
         return false;
       }
@@ -528,7 +529,7 @@ WaveReader::LoadListChunk(uint32_t aChunkSize,
     return false;
   }
 
-  nsAutoArrayPtr<char> chunk(new char[aChunkSize]);
+  auto chunk = MakeUnique<char[]>(aChunkSize);
   if (!ReadAll(chunk.get(), aChunkSize)) {
     return false;
   }
@@ -652,7 +653,7 @@ WaveReader::LoadAllChunks(nsAutoPtr<dom::HTMLMediaElement::MetadataTags> &aTags)
     static const int64_t MAX_CHUNK_SIZE = 1 << 16;
     static_assert(uint64_t(MAX_CHUNK_SIZE) < UINT_MAX / sizeof(char),
                   "MAX_CHUNK_SIZE too large for enumerator.");
-    nsAutoArrayPtr<char> chunk(new char[MAX_CHUNK_SIZE]);
+    auto chunk = MakeUnique<char[]>(MAX_CHUNK_SIZE);
     while (forward.value() > 0) {
       int64_t size = std::min(forward.value(), MAX_CHUNK_SIZE);
       if (!ReadAll(chunk.get(), size)) {
diff --git a/dom/media/webaudio/BiquadFilterNode.cpp b/dom/media/webaudio/BiquadFilterNode.cpp
index d87ff706f5c0..c89ebd5cfa88 100644
--- a/dom/media/webaudio/BiquadFilterNode.cpp
+++ b/dom/media/webaudio/BiquadFilterNode.cpp
@@ -12,6 +12,7 @@
 #include "WebAudioUtils.h"
 #include "blink/Biquad.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/UniquePtr.h"
 #include "AudioParamTimeline.h"
 
 namespace mozilla {
@@ -316,7 +317,7 @@ BiquadFilterNode::GetFrequencyResponse(const Float32Array& aFrequencyHz,
     return;
   }
 
-  nsAutoArrayPtr<float> frequencies(new float[length]);
+  auto frequencies = MakeUnique<float[]>(length);
   float* frequencyHz = aFrequencyHz.Data();
   const double nyquist = Context()->SampleRate() * 0.5;
 
@@ -338,7 +339,7 @@ BiquadFilterNode::GetFrequencyResponse(const Float32Array& aFrequencyHz,
 
   WebCore::Biquad biquad;
   SetParamsOnBiquad(biquad, Context()->SampleRate(), mType, freq, q, gain, detune);
-  biquad.getFrequencyResponse(int(length), frequencies, aMagResponse.Data(), aPhaseResponse.Data());
+  biquad.getFrequencyResponse(int(length), frequencies.get(), aMagResponse.Data(), aPhaseResponse.Data());
 }
 
 } // namespace dom
diff --git a/dom/media/webaudio/blink/DynamicsCompressor.cpp b/dom/media/webaudio/blink/DynamicsCompressor.cpp
index 10a285180a8f..57d511294ff3 100644
--- a/dom/media/webaudio/blink/DynamicsCompressor.cpp
+++ b/dom/media/webaudio/blink/DynamicsCompressor.cpp
@@ -69,8 +69,8 @@ size_t DynamicsCompressor::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSize
         }
     }
 
-    amount += m_sourceChannels.SizeOfExcludingThis(aMallocSizeOf);
-    amount += m_destinationChannels.SizeOfExcludingThis(aMallocSizeOf);
+    amount += aMallocSizeOf(m_sourceChannels.get());
+    amount += aMallocSizeOf(m_destinationChannels.get());
     amount += m_compressor.sizeOfExcludingThis(aMallocSizeOf);
     return amount;
 }
@@ -308,8 +308,8 @@ void DynamicsCompressor::setNumberOfChannels(unsigned numberOfChannels)
         m_postFilterPacks.AppendElement(new ZeroPoleFilterPack4());
     }
 
-    m_sourceChannels = new const float* [numberOfChannels];
-    m_destinationChannels = new float* [numberOfChannels];
+    m_sourceChannels = mozilla::MakeUnique<const float* []>(numberOfChannels);
+    m_destinationChannels = mozilla::MakeUnique<float* []>(numberOfChannels);
 
     m_compressor.setNumberOfChannels(numberOfChannels);
     m_numberOfChannels = numberOfChannels;
diff --git a/dom/media/webaudio/blink/DynamicsCompressor.h b/dom/media/webaudio/blink/DynamicsCompressor.h
index d0eac82f20d2..f460836b4957 100644
--- a/dom/media/webaudio/blink/DynamicsCompressor.h
+++ b/dom/media/webaudio/blink/DynamicsCompressor.h
@@ -35,6 +35,7 @@
 #include "nsTArray.h"
 #include "nsAutoPtr.h"
 #include "mozilla/MemoryReporting.h"
+#include "mozilla/UniquePtr.h"
 
 namespace mozilla {
 class AudioBlock;
@@ -115,8 +116,8 @@ protected:
     nsTArray<nsAutoPtr<ZeroPoleFilterPack4> > m_preFilterPacks;
     nsTArray<nsAutoPtr<ZeroPoleFilterPack4> > m_postFilterPacks;
 
-    nsAutoArrayPtr<const float*> m_sourceChannels;
-    nsAutoArrayPtr<float*> m_destinationChannels;
+    mozilla::UniquePtr<const float*[]> m_sourceChannels;
+    mozilla::UniquePtr<float*[]> m_destinationChannels;
 
     void setEmphasisStageParameters(unsigned stageIndex, float gain, float normalizedFrequency /* 0 -> 1 */);
     void setEmphasisParameters(float gain, float anchorFreq, float filterStageRatio);
diff --git a/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp b/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp
index eec04528caf3..4812c9a546b1 100644
--- a/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp
+++ b/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp
@@ -40,6 +40,7 @@ using namespace std;
 using namespace mozilla::dom; // for WebAudioUtils
 using mozilla::IsInfinite;
 using mozilla::IsNaN;
+using mozilla::MakeUnique;
 
 namespace WebCore {
 
@@ -78,7 +79,7 @@ size_t DynamicsCompressorKernel::sizeOfExcludingThis(mozilla::MallocSizeOf aMall
     size_t amount = 0;
     amount += m_preDelayBuffers.ShallowSizeOfExcludingThis(aMallocSizeOf);
     for (size_t i = 0; i < m_preDelayBuffers.Length(); i++) {
-        amount += m_preDelayBuffers[i].SizeOfExcludingThis(aMallocSizeOf);
+        amount += aMallocSizeOf(m_preDelayBuffers[i].get());
     }
 
     return amount;
@@ -91,7 +92,7 @@ void DynamicsCompressorKernel::setNumberOfChannels(unsigned numberOfChannels)
 
     m_preDelayBuffers.Clear();
     for (unsigned i = 0; i < numberOfChannels; ++i)
-        m_preDelayBuffers.AppendElement(new float[MaxPreDelayFrames]);
+      m_preDelayBuffers.AppendElement(MakeUnique<float[]>(MaxPreDelayFrames));
 }
 
 void DynamicsCompressorKernel::setPreDelayTime(float preDelayTime)
@@ -104,7 +105,7 @@ void DynamicsCompressorKernel::setPreDelayTime(float preDelayTime)
     if (m_lastPreDelayFrames != preDelayFrames) {
         m_lastPreDelayFrames = preDelayFrames;
         for (unsigned i = 0; i < m_preDelayBuffers.Length(); ++i)
-            memset(m_preDelayBuffers[i], 0, sizeof(float) * MaxPreDelayFrames);
+	  memset(m_preDelayBuffers[i].get(), 0, sizeof(float) * MaxPreDelayFrames);
 
         m_preDelayReadIndex = 0;
         m_preDelayWriteIndex = preDelayFrames;
@@ -387,7 +388,7 @@ void DynamicsCompressorKernel::process(float* sourceChannels[],
 
                 // Predelay signal, computing compression amount from un-delayed version.
                 for (unsigned i = 0; i < numberOfChannels; ++i) {
-                    float* delayBuffer = m_preDelayBuffers[i];
+                    float* delayBuffer = m_preDelayBuffers[i].get();
                     float undelayedSource = sourceChannels[i][frameIndex];
                     delayBuffer[preDelayWriteIndex] = undelayedSource;
 
@@ -453,7 +454,7 @@ void DynamicsCompressorKernel::process(float* sourceChannels[],
 
                 // Apply final gain.
                 for (unsigned i = 0; i < numberOfChannels; ++i) {
-                    float* delayBuffer = m_preDelayBuffers[i];
+                    float* delayBuffer = m_preDelayBuffers[i].get();
                     destinationChannels[i][frameIndex] = delayBuffer[preDelayReadIndex] * totalGain;
                 }
 
@@ -479,7 +480,7 @@ void DynamicsCompressorKernel::reset()
 
     // Predelay section.
     for (unsigned i = 0; i < m_preDelayBuffers.Length(); ++i)
-        memset(m_preDelayBuffers[i], 0, sizeof(float) * MaxPreDelayFrames);
+        memset(m_preDelayBuffers[i].get(), 0, sizeof(float) * MaxPreDelayFrames);
 
     m_preDelayReadIndex = 0;
     m_preDelayWriteIndex = DefaultPreDelayFrames;
diff --git a/dom/media/webaudio/blink/DynamicsCompressorKernel.h b/dom/media/webaudio/blink/DynamicsCompressorKernel.h
index b9453dc54ace..3ba69c243aca 100644
--- a/dom/media/webaudio/blink/DynamicsCompressorKernel.h
+++ b/dom/media/webaudio/blink/DynamicsCompressorKernel.h
@@ -32,6 +32,7 @@
 #include "nsTArray.h"
 #include "nsAutoPtr.h"
 #include "mozilla/MemoryReporting.h"
+#include "mozilla/UniquePtr.h"
 
 namespace WebCore {
 
@@ -89,7 +90,7 @@ protected:
     unsigned m_lastPreDelayFrames;
     void setPreDelayTime(float);
 
-    nsTArray<nsAutoArrayPtr<float> > m_preDelayBuffers;
+    nsTArray<mozilla::UniquePtr<float[]>> m_preDelayBuffers;
     int m_preDelayReadIndex;
     int m_preDelayWriteIndex;
 
diff --git a/dom/media/webm/EbmlComposer.cpp b/dom/media/webm/EbmlComposer.cpp
index a5dbecaa2cbf..1bda401e09c3 100644
--- a/dom/media/webm/EbmlComposer.cpp
+++ b/dom/media/webm/EbmlComposer.cpp
@@ -21,8 +21,8 @@ void EbmlComposer::GenerateHeader()
   // Write the EBML header.
   EbmlGlobal ebml;
   // The WEbM header default size usually smaller than 1k.
-  nsAutoArrayPtr<uint8_t> buffer(new uint8_t[DEFAULT_HEADER_SIZE +
-                                             mCodecPrivateData.Length()]);
+  auto buffer = MakeUnique<uint8_t[]>(DEFAULT_HEADER_SIZE +
+                                             mCodecPrivateData.Length());
   ebml.buf = buffer.get();
   ebml.offset = 0;
   writeHeader(&ebml);
diff --git a/dom/media/webrtc/MediaEngineDefault.cpp b/dom/media/webrtc/MediaEngineDefault.cpp
index a7c4715b04b8..9f7d272b87bc 100644
--- a/dom/media/webrtc/MediaEngineDefault.cpp
+++ b/dom/media/webrtc/MediaEngineDefault.cpp
@@ -6,6 +6,7 @@
 
 #include "nsCOMPtr.h"
 #include "mozilla/dom/File.h"
+#include "mozilla/UniquePtr.h"
 #include "nsILocalFile.h"
 #include "Layers.h"
 #include "ImageContainer.h"
@@ -314,7 +315,7 @@ public:
     // If we allow arbitrary frequencies, there's no guarantee we won't get rounded here
     // We could include an error term and adjust for it in generation; not worth the trouble
     //MOZ_ASSERT(mTotalLength * aFrequency == aSampleRate);
-    mAudioBuffer = new int16_t[mTotalLength];
+    mAudioBuffer = MakeUnique<int16_t[]>(mTotalLength);
     for (int i = 0; i < mTotalLength; i++) {
       // Set volume to -20db. It's from 32768.0 * 10^(-20/20) = 3276.8
       mAudioBuffer[i] = (3276.8f * sin(2 * M_PI * i / mTotalLength));
@@ -333,7 +334,7 @@ public:
       } else {
         processSamples = mTotalLength - mReadLength;
       }
-      memcpy(aBuffer, mAudioBuffer + mReadLength, processSamples * bytesPerSample);
+      memcpy(aBuffer, &mAudioBuffer[mReadLength], processSamples * bytesPerSample);
       aBuffer += processSamples;
       mReadLength += processSamples;
       remaining -= processSamples;
@@ -344,7 +345,7 @@ public:
   }
 
 private:
-  nsAutoArrayPtr<int16_t> mAudioBuffer;
+  UniquePtr<int16_t[]> mAudioBuffer;
   int16_t mTotalLength;
   int16_t mReadLength;
 };
diff --git a/dom/media/webspeech/synth/test/nsFakeSynthServices.cpp b/dom/media/webspeech/synth/test/nsFakeSynthServices.cpp
index 2f9507203a3d..0b72a4af5b7b 100644
--- a/dom/media/webspeech/synth/test/nsFakeSynthServices.cpp
+++ b/dom/media/webspeech/synth/test/nsFakeSynthServices.cpp
@@ -152,8 +152,8 @@ FakeDirectAudioSynth::Speak(const nsAString& aText, const nsAString& aUri,
       // Just an arbitrary multiplier. Pretend that each character is
       // synthesized to 40 frames.
       uint32_t frames_length = 40 * mText.Length();
-      nsAutoArrayPtr<int16_t> frames(new int16_t[frames_length]());
-      mTask->SendAudioNative(frames, frames_length);
+      auto frames = MakeUnique<int16_t[]>(frames_length);
+      mTask->SendAudioNative(frames.get(), frames_length);
 
       mTask->SendAudioNative(nullptr, 0);