Bug 1654475 - SharedSurface_SurfaceTexture: Only ReleaseTexImage if IsSingleBuffer r=jgilbert

SharedSurface_SurfaceTexture::ProducerReadReleaseImpl() handles java::GeckoSurfaceTexture. But how it work is very confusing. The GeckoSurfaceTexture is not SurfaceTexture of this class's GeckoSurface when current process is content process. SurfaceTexture of this class's GeckoSurface does not exist in this process. It exists in compositor's process. Then GeckoSurfaceTexture in this process is a sync surface that copies back the SurfaceTextrure from compositor's process.

Call ReleaseTexImage() only when Surface is single buffer mode, since it needs to be called only when Surface is single buffer mode.

Differential Revision: https://phabricator.services.mozilla.com/D84477

gfx/gl/SharedSurfaceEGL.cpp

@@ -207,6 +207,14 @@ void SharedSurface_SurfaceTexture::UnlockProdImpl() {
 }
 
 void SharedSurface_SurfaceTexture::ProducerReadReleaseImpl() {
+  // This GeckoSurfaceTexture is not SurfaceTexture of this class's GeckoSurface
+  // when current process is content process. In this case, SurfaceTexture of
+  // this class's GeckoSurface does not exist in this process. It exists in
+  // compositor's process. Then GeckoSurfaceTexture in this process is a sync
+  // surface that copies back the SurfaceTextrure from compositor's process. It
+  // was added by Bug 1486659. Then SurfaceTexture::UpdateTexImage() becomes
+  // very heavy weight, since it does copy back the SurfaceTextrure from
+  // compositor's process.
   java::GeckoSurfaceTexture::LocalRef surfaceTexture =
       java::GeckoSurfaceTexture::Lookup(mSurface->GetHandle());
   if (!surfaceTexture) {
@@ -214,7 +222,11 @@ void SharedSurface_SurfaceTexture::ProducerReadReleaseImpl() {
     return;
   }
   surfaceTexture->UpdateTexImage();
-  surfaceTexture->ReleaseTexImage();
+  // Non single buffer mode Surface does not need ReleaseTexImage() call.
+  // When SurfaceTexture is sync Surface, it might not be single buffer mode.
+  if (surfaceTexture->IsSingleBuffer()) {
+    surfaceTexture->ReleaseTexImage();
+  }
 }
 
 void SharedSurface_SurfaceTexture::Commit() {