Bug 1652550 - Disable RenderExternalTextureHost when BufferTextureHost is wrapped with GPUVideoTextureHost r=mattwoodrow

This patch also re-enables client storage for Nightly builds (gfx.webrender.enable-client-storage=true).

Differential Revision: https://phabricator.services.mozilla.com/D83375

gfx/layers/composite/GPUVideoTextureHost.cpp

@@ -39,7 +39,19 @@ TextureHost* GPUVideoTextureHost::EnsureWrappedTextureHost() {
   mWrappedTextureHost =
       VideoBridgeParent::GetSingleton(sd.source())->LookupTexture(sd.handle());
 
-  if (mWrappedTextureHost && mExternalImageId.isSome()) {
+  if (!mWrappedTextureHost) {
+    return nullptr;
+  }
+
+  if (mWrappedTextureHost->AsBufferTextureHost()) {
+    // TODO(miko): This code path is taken when WebRenderTextureHost wraps
+    // GPUVideoTextureHost, which wraps BufferTextureHost.
+    // Because this creates additional copies of the texture data, we should not
+    // do this.
+    mWrappedTextureHost->AsBufferTextureHost()->DisableExternalTextures();
+  }
+
+  if (mExternalImageId.isSome()) {
     // External image id is allocated by mWrappedTextureHost.
     mWrappedTextureHost->EnsureRenderTexture(Nothing());
     MOZ_ASSERT(mWrappedTextureHost->mExternalImageId.isSome());

gfx/layers/composite/TextureHost.h

@@ -830,6 +830,7 @@ class BufferTextureHost : public TextureHost {
   };
 
   bool CanUnlock() { return !mFirstSource || mFirstSource->Sync(false); }
+  void DisableExternalTextures() { mUseExternalTextures = false; }
 
  protected:
   bool UseExternalTextures() const { return mUseExternalTextures; }

modules/libpref/init/StaticPrefList.yaml

@@ -4507,7 +4507,7 @@
 #ifdef XP_MACOSX
 - name: gfx.webrender.enable-client-storage
   type: bool
-  value: false
+  value: @IS_NIGHTLY_BUILD@
   mirror: once
 #endif