Use shared_from_this in GlTextureBuffer::GetReadView, GetWriteView

This ensures that the callbacks in GlTextureView won't call an expired object, even if user code holds a GlTextureView after releasing the buffer.

Note that GlTextureBuffer is not always held by a shared_ptr, but it always is when GpuBuffer calls GetRead/WriteView on it. An alternative solution would have been to have GpuBuffer pass its shared_ptr<GlTextureBuffer> to the view method, which could have been implemented with some compile-time logic to detect whether the method expects such an argument. However, that doesn't seem necessary.

PiperOrigin-RevId: 489611843

mediapipe/gpu/gl_texture_buffer.h

@@ -35,7 +35,8 @@ class GlCalculatorHelperImpl;
 // Implements a GPU memory buffer as an OpenGL texture. For internal use.
 class GlTextureBuffer
     : public internal::GpuBufferStorageImpl<
-          GlTextureBuffer, internal::ViewProvider<GlTextureView>> {
+          GlTextureBuffer, internal::ViewProvider<GlTextureView>>,
+      public std::enable_shared_from_this<GlTextureBuffer> {
  public:
   // This is called when the texture buffer is deleted. It is passed a sync
   // token created at that time on the GlContext. If the GlTextureBuffer has