Rename and extract Context. (#8528)

* Rename `GenericParameter` to `Context`.
* Rename header file to reflect the change.
* Rename all references.

tests/cpp/common/test_json.cc

@@ -590,7 +590,7 @@ TEST(Json, DISABLED_RoundTripExhaustive) {
     }
   };
   int64_t int32_max = static_cast<int64_t>(std::numeric_limits<uint32_t>::max());
-  GenericParameter ctx;
+  Context ctx;
   common::ParallelFor(int32_max, ctx.Threads(), [&](auto i) { test(static_cast<uint32_t>(i)); });
 }
 

tests/cpp/common/test_linalg.cc

@@ -2,7 +2,7 @@
  * Copyright 2021 by XGBoost Contributors
  */
 #include <gtest/gtest.h>
-#include <xgboost/generic_parameters.h>
+#include <xgboost/context.h>
 #include <xgboost/host_device_vector.h>
 #include <xgboost/linalg.h>
 
@@ -13,7 +13,7 @@
 namespace xgboost {
 namespace linalg {
 namespace {
-auto kCpuId = GenericParameter::kCpuId;
+auto kCpuId = Context::kCpuId;
 }
 
 auto MakeMatrixFromTest(HostDeviceVector<float> *storage, size_t n_rows, size_t n_cols) {

tests/cpp/common/test_linalg.cu

@@ -4,7 +4,7 @@
 #include <gtest/gtest.h>
 
 #include "../../../src/common/linalg_op.cuh"
-#include "xgboost/generic_parameters.h"
+#include "xgboost/context.h"
 #include "xgboost/linalg.h"
 
 namespace xgboost {
@@ -21,7 +21,7 @@ void TestElementWiseKernel() {
     ASSERT_FALSE(t.CContiguous());
     ElementWiseTransformDevice(t, [] __device__(size_t i, float) { return i; });
     // CPU view
-    t = l.View(GenericParameter::kCpuId).Slice(linalg::All(), 1, linalg::All());
+    t = l.View(Context::kCpuId).Slice(linalg::All(), 1, linalg::All());
     size_t k = 0;
     for (size_t i = 0; i < l.Shape(0); ++i) {
       for (size_t j = 0; j < l.Shape(2); ++j) {
@@ -41,7 +41,7 @@ void TestElementWiseKernel() {
     ElementWiseTransformDevice(t, [] XGBOOST_DEVICE(size_t i, float) { return i; });
     ASSERT_TRUE(t.CContiguous());
     // CPU view
-    t = l.View(GenericParameter::kCpuId);
+    t = l.View(Context::kCpuId);
 
     size_t ind = 0;
     for (size_t i = 0; i < l.Shape(0); ++i) {

tests/cpp/common/test_stats.cc

@@ -2,7 +2,7 @@
  * Copyright 2022 by XGBoost Contributors
  */
 #include <gtest/gtest.h>
-#include <xgboost/generic_parameters.h>
+#include <xgboost/context.h>
 
 #include "../../../src/common/stats.h"
 

tests/cpp/common/test_stats.cu

@@ -2,12 +2,13 @@
  * Copyright 2022 by XGBoost Contributors
  */
 #include <gtest/gtest.h>
+
 #include <utility>
 #include <vector>
 
 #include "../../../src/common/stats.cuh"
 #include "xgboost/base.h"
-#include "xgboost/generic_parameters.h"
+#include "xgboost/context.h"
 #include "xgboost/host_device_vector.h"
 #include "xgboost/linalg.h"