Backed out changeset af41b9549456 (bug 1630389) for causing mass Windows failures.

CLOSED TREE

gfx/thebes/gfxWindowsPlatform.cpp

@@ -1625,14 +1625,11 @@ class D3DVsyncSource final : public VsyncSource {
         : mPrevVsync(TimeStamp::Now()),
           mVsyncEnabledLock("D3DVsyncEnabledLock"),
           mVsyncEnabled(false),
-          mWaitVBlankMonitor(NULL),
-          mIsWindows10OrLater(false) {
+          mWaitVBlankMonitor(NULL) {
       mVsyncThread = new base::Thread("WindowsVsyncThread");
       MOZ_RELEASE_ASSERT(mVsyncThread->Start(),
                          "GFX: Could not start Windows vsync thread");
       SetVsyncRate();
-
-      mIsWindows10OrLater = IsWin10OrLater();
     }
 
     void SetVsyncRate() {
@@ -1804,8 +1801,7 @@ class D3DVsyncSource final : public VsyncSource {
         }
 
         HRESULT hr = E_FAIL;
-        if (mIsWindows10OrLater &&
-            !StaticPrefs::gfx_vsync_force_disable_waitforvblank()) {
+        if (StaticPrefs::gfx_vsync_use_waitforvblank()) {
           UpdateVBlankOutput();
           if (mWaitVBlankOutput) {
             hr = mWaitVBlankOutput->WaitForVBlank();
@@ -1890,7 +1886,6 @@ class D3DVsyncSource final : public VsyncSource {
 
     HMONITOR mWaitVBlankMonitor;
     RefPtr<IDXGIOutput> mWaitVBlankOutput;
-    bool mIsWindows10OrLater;
   };  // end d3dvsyncdisplay
 
   D3DVsyncSource() { mPrimaryDisplay = new D3DVsyncDisplay(); }

modules/libpref/init/StaticPrefList.yaml

@@ -3989,7 +3989,7 @@
   value: 10
   mirror: once
 
-- name: gfx.vsync.force-disable-waitforvblank
+- name: gfx.vsync.use-waitforvblank
   type: RelaxedAtomicBool
   value: false
   mirror: always