Bug 1710486 - Fix InProcessWinCompositorWidget locking to always release the present lock. r=cmartin

Otherwise we may hang when drawing transparent popups.

Differential Revision: https://phabricator.services.mozilla.com/D114766

widget/windows/InProcessWinCompositorWidget.cpp

@@ -66,11 +66,10 @@ InProcessWinCompositorWidget::InProcessWinCompositorWidget(
 }
 
 void InProcessWinCompositorWidget::OnDestroyWindow() {
-  EnterPresentLock();
+  gfx::CriticalSectionAutoEnter presentLock(&mPresentLock);
   MutexAutoLock lock(mTransparentSurfaceLock);
   mTransparentSurface = nullptr;
   mMemoryDC = nullptr;
-  LeavePresentLock();
 }
 
 bool InProcessWinCompositorWidget::OnWindowResize(
@@ -266,7 +265,7 @@ void InProcessWinCompositorWidget::CreateTransparentSurface(
 
 void InProcessWinCompositorWidget::UpdateTransparency(
     nsTransparencyMode aMode) {
-  EnterPresentLock();
+  gfx::CriticalSectionAutoEnter presentLock(&mPresentLock);
   MutexAutoLock lock(mTransparentSurfaceLock);
   if (mTransparencyMode == aMode) {
     return;
@@ -279,7 +278,6 @@ void InProcessWinCompositorWidget::UpdateTransparency(
   if (mTransparencyMode == eTransparencyTransparent) {
     EnsureTransparentSurface();
   }
-  LeavePresentLock();
 }
 
 bool InProcessWinCompositorWidget::HasGlass() const {
@@ -292,7 +290,7 @@ bool InProcessWinCompositorWidget::HasGlass() const {
 }
 
 void InProcessWinCompositorWidget::ClearTransparentWindow() {
-  EnterPresentLock();
+  gfx::CriticalSectionAutoEnter presentLock(&mPresentLock);
   MutexAutoLock lock(mTransparentSurfaceLock);
   if (!mTransparentSurface) {
     return;
@@ -310,7 +308,6 @@ void InProcessWinCompositorWidget::ClearTransparentWindow() {
     drawTarget->ClearRect(Rect(0, 0, size.width, size.height));
     RedrawTransparentWindow();
   }
-  LeavePresentLock();
 }
 
 bool InProcessWinCompositorWidget::RedrawTransparentWindow() {