Enforce no uncleared OES external textures. Clear in AVDA, not GVD.

media/gpu/ipc/service/gpu_video_decode_accelerator.cc

Index: media/gpu/ipc/service/gpu_video_decode_accelerator.cc
diff --git a/media/gpu/ipc/service/gpu_video_decode_accelerator.cc b/media/gpu/ipc/service/gpu_video_decode_accelerator.cc
index 1470a1254cd4bf9c8357878c246c693058ca7704..cdc67c2e7540bd8710dbfdea6e8739219fe6c7c6 100644
--- a/media/gpu/ipc/service/gpu_video_decode_accelerator.cc
+++ b/media/gpu/ipc/service/gpu_video_decode_accelerator.cc
@@ -519,8 +519,14 @@ void GpuVideoDecodeAccelerator::SetTextureCleared(const Picture& picture) {
     GLenum target = texture_ref->texture()->target();
     gpu::gles2::TextureManager* texture_manager =
         stub_->decoder()->GetContextGroup()->texture_manager();
-    DCHECK(!texture_ref->texture()->IsLevelCleared(target, 0));
-    texture_manager->SetLevelCleared(texture_ref.get(), target, 0, true);
+
+    // External textures are a special case and expected to already be cleared.
+    if (target == GL_TEXTURE_EXTERNAL_OES) {
+      DCHECK(texture_ref->texture()->IsLevelCleared(target, 0));
+    } else {
+      DCHECK(!texture_ref->texture()->IsLevelCleared(target, 0));
+      texture_manager->SetLevelCleared(texture_ref.get(), target, 0, true);
+    }
   }
   uncleared_textures_.erase(it);
 }