Bug 1103824 - Back out changeset for causing regression reported in bug 1176499.

dom/media/CubebUtils.cpp

@@ -104,13 +104,12 @@ void InitPreferredSampleRate()
 cubeb* GetCubebContextUnlocked()
 {
   sMutex.AssertCurrentThreadOwns();
-  if (!sCubebContext) {
-    MOZ_ASSERT(NS_IsMainThread());
-    if (cubeb_init(&sCubebContext, "CubebUtils") != CUBEB_OK) {
-      NS_WARNING("cubeb_init failed");
-    }
+  if (sCubebContext ||
+      cubeb_init(&sCubebContext, "CubebUtils") == CUBEB_OK) {
+    return sCubebContext;
   }
-  return sCubebContext;
+  NS_WARNING("cubeb_init failed");
+  return nullptr;
 }
 
 uint32_t GetCubebLatency()

dom/media/MediaDecoder.cpp

@@ -10,7 +10,6 @@
 #include <limits>
 #include "nsIObserver.h"
 #include "nsTArray.h"
-#include "CubebUtils.h"
 #include "VideoUtils.h"
 #include "MediaDecoderStateMachine.h"
 #include "ImageContainer.h"
@@ -402,11 +401,6 @@ bool MediaDecoder::Init(MediaDecoderOwner* aOwner)
   mOwner = aOwner;
   mVideoFrameContainer = aOwner->GetVideoFrameContainer();
   MediaShutdownManager::Instance().Register(this);
-  // We don't use the cubeb context yet, but need to ensure it is created on
-  // the main thread.
-  if (!CubebUtils::GetCubebContext()) {
-    NS_WARNING("Audio backend initialization failed.");
-  }
   return true;
 }
 

dom/media/webaudio/AudioContext.cpp

@@ -110,11 +110,6 @@ AudioContext::AudioContext(nsPIDOMWindow* aWindow,
   // call them after mDestination has been set up.
   mDestination->CreateAudioChannelAgent();
   mDestination->SetIsOnlyNodeForContext(true);
-  // We don't use the cubeb context yet, but need to ensure it is created on
-  // the main thread.
-  if (!aIsOffline && !CubebUtils::GetCubebContext()) {
-    NS_WARNING("Audio backend initialization failed.");
-  }
 }
 
 AudioContext::~AudioContext()

media/libcubeb/src/cubeb_wasapi.cpp

@@ -144,17 +144,28 @@ private:
 };
 
 struct auto_com {
-  auto_com(DWORD dwCoInit = COINIT_MULTITHREADED) {
-    result = CoInitializeEx(NULL, dwCoInit);
+  auto_com() {
+    result = CoInitializeEx(NULL, COINIT_MULTITHREADED);
   }
   ~auto_com() {
-    if (ok()) {
+    if (result == RPC_E_CHANGED_MODE) {
+      // This is not an error, COM was not initialized by this function, so it is
+      // not necessary to uninit it.
+      LOG("COM already initialized in STA.\n");
+    } else if (result == S_FALSE) {
+      // This is not an error. We are allowed to call CoInitializeEx more than
+      // once, as long as it is matches by an CoUninitialize call.
+      // We do that in the dtor which is guaranteed to be called.
+      LOG("COM already initialized in MTA\n");
+    }
+    if (SUCCEEDED(result)) {
       CoUninitialize();
     }
   }
   bool ok() {
-    return SUCCEEDED(result);
+    return result == RPC_E_CHANGED_MODE || SUCCEEDED(result);
   }
+private:
   HRESULT result;
 };
 
@@ -481,7 +492,6 @@ wasapi_stream_render_loop(LPVOID stream)
   auto_com com;
   if (!com.ok()) {
     LOG("COM initialization failed on render_loop thread.\n");
-    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
     return 0;
   }
 
@@ -678,58 +688,28 @@ HRESULT get_default_endpoint(IMMDevice ** device)
 
   return ERROR_SUCCESS;
 }
-
-owned_critical_section g_first_init_lock;
-bool g_first_init = false;
 } // namespace anonymous
 
 extern "C" {
 int wasapi_init(cubeb ** context, char const * context_name)
 {
-  auto_lock lock(&g_first_init_lock);
-  if (!g_first_init) {
-    // Per the MSDN documentation for IAudioClient, the first use *must* be made from an STA thread.
-    auto_com com(COINIT_APARTMENTTHREADED);
-    if (FAILED(com.result)) {
-      return CUBEB_ERROR;
-    }
-
-    /* We don't use the device yet, but need to make sure we can initialize one
-       so that this backend is not incorrectly enabled on platforms that don't
-       support WASAPI. */
-    IMMDevice * device;
-    HRESULT hr = get_default_endpoint(&device);
-    if (FAILED(hr)) {
-      LOG("Could not get device: %x\n", hr);
-      return CUBEB_ERROR;
-    }
-    IAudioClient * client;
-    hr = device->Activate(__uuidof(IAudioClient),
-                          CLSCTX_INPROC_SERVER,
-                          NULL, (void **)&client);
-    if (SUCCEEDED(hr)) {
-      WAVEFORMATEX * mix_format;
-      hr = client->GetMixFormat(&mix_format);
-      if (SUCCEEDED(hr)) {
-        hr = client->Initialize(AUDCLNT_SHAREMODE_SHARED,
-                                AUDCLNT_STREAMFLAGS_EVENTCALLBACK |
-                                AUDCLNT_STREAMFLAGS_NOPERSIST,
-                                ms_to_hns(100),
-                                0,
-                                mix_format,
-                                NULL);
-        CoTaskMemFree(mix_format);
-        g_first_init = true;
-      }
-      SafeRelease(client);
-    }
-    SafeRelease(device);
-    if (FAILED(hr)) {
-      LOG("Could not initialize IAudioClient: %x\n", hr);
-      return CUBEB_ERROR;
-    }
+  HRESULT hr;
+  auto_com com;
+  if (!com.ok()) {
+    return CUBEB_ERROR;
   }
 
+  /* We don't use the device yet, but need to make sure we can initialize one
+     so that this backend is not incorrectly enabled on platforms that don't
+     support WASAPI. */
+  IMMDevice * device;
+  hr = get_default_endpoint(&device);
+  if (FAILED(hr)) {
+    LOG("Could not get device.\n");
+    return CUBEB_ERROR;
+  }
+  SafeRelease(device);
+
   cubeb * ctx = (cubeb *)calloc(1, sizeof(cubeb));
 
   ctx->ops = &wasapi_ops;
@@ -804,8 +784,10 @@ wasapi_get_max_channel_count(cubeb * ctx, uint32_t * max_channels)
   HRESULT hr;
   IAudioClient * client;
   WAVEFORMATEX * mix_format;
-  XASSERT(g_first_init);
-  auto_com com; /* don't care what COM mode we're in here */
+  auto_com com;
+  if (!com.ok()) {
+    return CUBEB_ERROR;
+  }
 
   XASSERT(ctx && max_channels);
 
@@ -843,8 +825,10 @@ wasapi_get_min_latency(cubeb * ctx, cubeb_stream_params params, uint32_t * laten
   HRESULT hr;
   IAudioClient * client;
   REFERENCE_TIME default_period;
-  XASSERT(g_first_init);
-  auto_com com; /* don't care what COM mode we're in here */
+  auto_com com;
+  if (!com.ok()) {
+    return CUBEB_ERROR;
+  }
 
   IMMDevice * device;
   hr = get_default_endpoint(&device);
@@ -888,8 +872,10 @@ wasapi_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate)
   HRESULT hr;
   IAudioClient * client;
   WAVEFORMATEX * mix_format;
-  XASSERT(g_first_init);
-  auto_com com; /* don't care what COM mode we're in here */
+  auto_com com;
+  if (!com.ok()) {
+    return CUBEB_ERROR;
+  }
 
   IMMDevice * device;
   hr = get_default_endpoint(&device);