import changes from `dev' branch of rmottola/Arctic-Fox:

- formatting (49c876691)
- adapted  Bug 1163227: Part5: Increase verbosity content for debugging purposes. r=cpearce (cfca0b7bf)
- Bug 1184634 - Rename MediaPromise to MozPromise. r=gerald (e9617bf70)
- space (c5bafde74)
- Bug 1158293 - Fix ResumeStateMachine()'s seek handling r=cpearce (67dbe7dfc)
- reapply part of Bug 1158448 Part 2 (a953e6c6b)
- Bug 1184634 - Rename "TaskQueue()" accessor to "OwnerThread()". r=gerald (118965bae)
- Bug 1145411: Reduce Apple audio decoder verbosity. r=mattwoodrow (a9f2c4092)
- Bug 1174055 - Remove some now uncalled WMF functions. r=jya (8cddc9d0e)
- Bug 1179094: Use TimeUnit in PlatformDecoderModule. r=cpearce (3d8fd9cd7)
- align warnings to Bug 1154133 - Remove sync dispatches in EMEDecryptor, and mark MediaTaskQueue::SyncDispatch as deprecated. (d93e2f431)
- align some permissions and comments (54eb9e910)
- Bug 1155268 - Add checked methods to convert from an AbstractThread to a concrete type. r=cpearce (5deff5f04)
- align comment (c508b1aaf)
- Bug 857895 - Only enforce tail dispatch if both source and dest support it. r=bholley (2e6d03096)
- Bug 1184634 - Rename MediaTaskQueue to TaskQueue. r=gerald (5f18c2616)
- Bug 1127656 - Remove class inheritance hierarchy from gonk PlatformDeocdeModule. r=ajones (eebf0eb20)
- Bug 1184634 - Move various includes into the mozilla namespace. r=gerald (a9b516578)
- Bug 1190636 - Replace AutoStringVector with Rooted usage; r=njn (5d287ee81)
- Bug 1190911 - Replace AutoIdValueVector with normal Rooted usage; r=jonco (b6c8ce668)
- Bug 1149343 - Followup to fix bustage on a CLOSED TREE (f20f9f1a2)
- Bug 1172841. Set number of WMF decoder threads based on CPU count. r=cpearce (af74b7654)
- Bug 1166760 - Query audio sampling rate & channel number from codec. r=sotaro (ee5fb569a)
-  Bug 1175071 - Remove those codes which handles ADTS. r=jya. (00b1d3dad)
- Bug 1178682 - Reject the decoded sample if timestamp is revert. r=sotaro (4cd029e8c)

dom/media/platforms/wmf/WMFDecoderModule.cpp

@@ -17,14 +17,16 @@
 #include "nsServiceManagerUtils.h"
 #include "nsIGfxInfo.h"
 #include "GfxDriverInfo.h"
+#include "gfxWindowsPlatform.h"
 #include "nsServiceManagerUtils.h"      // for do_GetService
 #include "MediaInfo.h"
-#include "gfxPlatform.h"
+#include "prsystem.h"
 
 namespace mozilla {
 
 static bool sIsWMFEnabled = false;
 static bool sDXVAEnabled = false;
+static int  sNumDecoderThreads = -1;
 
 WMFDecoderModule::WMFDecoderModule()
   : mWMFInitialized(false)
@@ -45,6 +47,25 @@ WMFDecoderModule::DisableHardwareAcceleration()
   sDXVAEnabled = false;
 }
 
+static void
+SetNumOfDecoderThreads()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Preferences can only be read on main thread");
+  int32_t numCores = PR_GetNumberOfProcessors();
+
+  // If we have more than 4 cores, let the decoder decide how many threads.
+  // On an 8 core machine, WMF chooses 4 decoder threads
+  const int WMF_DECODER_DEFAULT = -1;
+  int32_t prefThreadCount = Preferences::GetInt("media.wmf.decoder.thread-count", -1);
+  if (prefThreadCount != WMF_DECODER_DEFAULT) {
+    sNumDecoderThreads = std::max(prefThreadCount, 1);
+  } else if (numCores > 4) {
+    sNumDecoderThreads = WMF_DECODER_DEFAULT;
+  } else {
+    sNumDecoderThreads = std::max(numCores - 1, 1);
+  }
+}
+
 /* static */
 void
 WMFDecoderModule::Init()
@@ -52,6 +73,14 @@ WMFDecoderModule::Init()
   MOZ_ASSERT(NS_IsMainThread(), "Must be on main thread.");
   sIsWMFEnabled = Preferences::GetBool("media.windows-media-foundation.enabled", false);
   sDXVAEnabled = gfxPlatform::GetPlatform()->CanUseHardwareVideoDecoding();
+  SetNumOfDecoderThreads();
+}
+
+/* static */
+int
+WMFDecoderModule::GetNumDecoderThreads()
+{
+  return sNumDecoderThreads;
 }
 
 nsresult
@@ -67,7 +96,7 @@ already_AddRefed<MediaDataDecoder>
 WMFDecoderModule::CreateVideoDecoder(const VideoInfo& aConfig,
                                      layers::LayersBackend aLayersBackend,
                                      layers::ImageContainer* aImageContainer,
-                                     FlushableMediaTaskQueue* aVideoTaskQueue,
+                                     FlushableTaskQueue* aVideoTaskQueue,
                                      MediaDataDecoderCallback* aCallback)
 {
   nsRefPtr<MediaDataDecoder> decoder =
@@ -82,7 +111,7 @@ WMFDecoderModule::CreateVideoDecoder(const VideoInfo& aConfig,
 
 already_AddRefed<MediaDataDecoder>
 WMFDecoderModule::CreateAudioDecoder(const AudioInfo& aConfig,
-                                     FlushableMediaTaskQueue* aAudioTaskQueue,
+                                     FlushableTaskQueue* aAudioTaskQueue,
                                      MediaDataDecoderCallback* aCallback)
 {
   nsRefPtr<MediaDataDecoder> decoder =