all: import "context" instead of "golang.org/x/net/context"

There is no need to depend on the old context package now that the
minimum Go version is 1.7. The move to "context" eliminates our weird
vendoring setup. Some vendored code still uses golang.org/x/net/context
and it is now vendored in the normal way.

This change triggered new vet checks around context.WithTimeout which
didn't fire with golang.org/x/net/context.

eth/api.go

@@ -19,6 +19,7 @@ package eth
 import (
 	"bytes"
 	"compress/gzip"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -39,7 +40,6 @@ import (
 	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 const defaultTraceTimeout = 5 * time.Second

eth/api_backend.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -33,7 +34,6 @@ import (
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // EthApiBackend implements ethapi.Backend for full nodes

eth/bind.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum"
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // ContractBackend implements bind.ContractBackend with direct calls to Ethereum

eth/downloader/api.go

@@ -17,12 +17,12 @@
 package downloader
 
 import (
+	"context"
 	"sync"
 
 	ethereum "github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // PublicDownloaderAPI provides an API which gives information about the current synchronisation status.

eth/filters/api.go

@@ -17,6 +17,7 @@
 package filters
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -24,8 +25,6 @@ import (
 	"sync"
 	"time"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/types"

eth/filters/filter.go

@@ -17,10 +17,10 @@
 package filters
 
 import (
+	"context"
 	"math"
-	"time"
-
 	"math/big"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
@@ -28,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 type Backend interface {

eth/filters/filter_system.go

@@ -19,6 +19,7 @@
 package filters
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"sync"
@@ -29,7 +30,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // Type determines the kind of filter and is used to put the filter in to
@@ -372,7 +372,8 @@ func (es *EventSystem) lightFilterNewHead(newHeader *types.Header, callBack func
 func (es *EventSystem) lightFilterLogs(header *types.Header, addresses []common.Address, topics [][]common.Hash, remove bool) []*types.Log {
 	if bloomFilter(header.Bloom, addresses, topics) {
 		// Get the logs of the block
-		ctx, _ := context.WithTimeout(context.Background(), time.Second*5)
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+		defer cancel()
 		receipts, err := es.backend.GetReceipts(ctx, header.Hash())
 		if err != nil {
 			return nil

eth/filters/filter_system_test.go

@@ -17,13 +17,12 @@
 package filters
 
 import (
+	"context"
 	"math/big"
 	"reflect"
 	"testing"
 	"time"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"

eth/filters/filter_test.go

@@ -17,13 +17,12 @@
 package filters
 
 import (
+	"context"
 	"io/ioutil"
 	"math/big"
 	"os"
 	"testing"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"

eth/gasprice/lightprice.go

@@ -17,6 +17,7 @@
 package gasprice
 
 import (
+	"context"
 	"math/big"
 	"sort"
 	"sync"
@@ -24,7 +25,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 const (