Reduce AudioDeviceThread stack size to 256kB.

It ought to be enough for everyone! Tests on Window show that normal
audio playback only uses 4kB and WebRTC uses ~68kB, so 256kB
seems enough to cover our use cases.

Fixed: 1141563
Change-Id: I4f119c3985347b45b4d934432792efb0d6e2dc1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500432
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821449}

media/audio/audio_device_thread.cc

@@ -8,6 +8,7 @@
 
 #include "base/check_op.h"
 #include "base/system/sys_info.h"
+#include "build/build_config.h"
 
 namespace media {
 
@@ -45,8 +46,17 @@ AudioDeviceThread::AudioDeviceThread(Callback* callback,
     : callback_(callback),
       thread_name_(thread_name),
       socket_(std::move(socket)) {
-  CHECK(base::PlatformThread::CreateWithPriority(0, this, &thread_handle_,
-                                                 thread_priority));
+#if defined(ARCH_CPU_X86)
+  // Audio threads don't need a huge stack, they don't have a message loop and
+  // they are used exclusively for polling the next frame of audio. See
+  // https://crbug.com/1141563 for discussion.
+  constexpr size_t kStackSize = 256 * 1024;
+#else
+  constexpr size_t kStackSize = 0;  // Default.
+#endif
+
+  CHECK(base::PlatformThread::CreateWithPriority(
+      kStackSize, this, &thread_handle_, thread_priority));
 
   DCHECK(!thread_handle_.is_null());
 }