Sketching from adapters (#5365)

* Sketching from adapters

* Add weights test

src/common/hist_util.h

@@ -179,16 +179,14 @@ class DenseCuts  : public CutsBuilder {
   void Build(DMatrix* p_fmat, uint32_t max_num_bins) override;
 };
 
-// FIXME(trivialfis): Merge this into generic cut builder.
-/*! \brief Builds the cut matrix on the GPU.
- *
- *  \return The row stride across the entire dataset.
- */
-size_t DeviceSketch(int device,
-                    int max_bin,
-                    int gpu_batch_nrows,
-                    DMatrix* dmat,
-                    HistogramCuts* hmat);
+
+HistogramCuts DeviceSketch(int device, DMatrix* dmat, int max_bins,
+                           size_t sketch_batch_num_elements = 10000000);
+
+template <typename AdapterT>
+HistogramCuts AdapterDeviceSketch(AdapterT* adapter, int num_bins,
+                                  float missing,
+                                  size_t sketch_batch_num_elements = 10000000);
 
 /*!
  * \brief preprocessed global index matrix, in CSR format