simplify the allocator API

Exposing NewAllocator and AllocatorOption was unnecessary, and it made
the API more complex to use and understand.

Instead, have users call NewExecAllocator directly. This removes some
code, and simplifies the examples and tests.

allocate.go

@@ -31,30 +31,9 @@ type Allocator interface {
 	Wait()
 }
 
-// NewAllocator creates a new allocator context, suitable for use with
+// setupExecAllocator is similar to NewExecAllocator, but it allows NewContext
-// NewContext or Run.
+// to create the allocator without the unnecessary context layer.
-func NewAllocator(parent context.Context, opts ...AllocatorOption) (context.Context, context.CancelFunc) {
+func setupExecAllocator(opts ...ExecAllocatorOption) *ExecAllocator {
-	ctx, cancel := context.WithCancel(parent)
-	c := &Context{}
-
-	for _, o := range opts {
-		o(&c.Allocator)
-	}
-
-	ctx = context.WithValue(ctx, contextKey{}, c)
-	cancelWait := func() {
-		cancel()
-		c.Allocator.Wait()
-	}
-	return ctx, cancelWait
-}
-
-// AllocatorOption is a allocator option.
-type AllocatorOption func(*Allocator)
-
-// WithExecAllocator returns an AllocatorOption which sets up an ExecAllocator.
-func WithExecAllocator(opts ...ExecAllocatorOption) func(*Allocator) {
-	return func(p *Allocator) {
 	ep := &ExecAllocator{
 		initFlags: make(map[string]interface{}),
 	}
@@ -64,8 +43,21 @@ func WithExecAllocator(opts ...ExecAllocatorOption) func(*Allocator) {
 	if ep.execPath == "" {
 		ep.execPath = findExecPath()
 	}
-		*p = ep
+	return ep
+}
+
+// NewExecAllocator creates a new context set up with an ExecAllocator, suitable
+// for use with NewContext or Run.
+func NewExecAllocator(parent context.Context, opts ...ExecAllocatorOption) (context.Context, context.CancelFunc) {
+	ctx, cancel := context.WithCancel(parent)
+	c := &Context{Allocator: setupExecAllocator(opts...)}
+
+	ctx = context.WithValue(ctx, contextKey{}, c)
+	cancelWait := func() {
+		cancel()
+		c.Allocator.Wait()
 	}
+	return ctx, cancelWait
 }
 
 // ExecAllocatorOption is a exec allocator option.

allocate_test.go

@@ -9,7 +9,7 @@ import (
 func TestExecAllocator(t *testing.T) {
 	t.Parallel()
 
-	poolCtx, poolCancel := NewAllocator(context.Background(), WithExecAllocator(allocOpts...))
+	poolCtx, poolCancel := NewExecAllocator(context.Background(), allocOpts...)
 	defer poolCancel()
 
 	// TODO: test that multiple child contexts are run in different
@@ -41,7 +41,7 @@ func TestExecAllocator(t *testing.T) {
 func TestExecAllocatorCancelParent(t *testing.T) {
 	t.Parallel()
 
-	poolCtx, poolCancel := NewAllocator(context.Background(), WithExecAllocator(allocOpts...))
+	poolCtx, poolCancel := NewExecAllocator(context.Background(), allocOpts...)
 	defer poolCancel()
 
 	// TODO: test that multiple child contexts are run in different

chromedp_test.go

@@ -53,7 +53,7 @@ func TestMain(m *testing.M) {
 		allocOpts = append(allocOpts, NoSandbox)
 	}
 
-	allocCtx, cancel := NewAllocator(context.Background(), WithExecAllocator(allocOpts...))
+	allocCtx, cancel := NewExecAllocator(context.Background(), allocOpts...)
 
 	// start the browser
 	browserCtx, _ = NewContext(allocCtx)

context.go

@@ -62,11 +62,11 @@ func NewContext(parent context.Context, opts ...ContextOption) (context.Context,
 		o(c)
 	}
 	if c.Allocator == nil {
-		WithExecAllocator(
+		c.Allocator = setupExecAllocator(
 			NoFirstRun,
 			NoDefaultBrowserCheck,
 			Headless,
-		)(&c.Allocator)
+		)
 	}
 
 	ctx = context.WithValue(ctx, contextKey{}, c)
@@ -113,8 +113,8 @@ func FromContext(ctx context.Context) *Context {
 }
 
 // Run runs an action against the provided context. The provided context must
-// contain a valid Allocator; typically, that will be created via NewContext or
+// contain a valid Allocator; typically, that will be created via NewContext, or
-// NewAllocator.
+// via one of the allocator constructors like NewExecAllocator.
 func Run(ctx context.Context, actions ...Action) error {
 	c := FromContext(ctx)
 	if c == nil || c.Allocator == nil {

example_test.go

@@ -45,8 +45,7 @@ func ExampleExecAllocator() {
 		chromedp.UserDataDir(dir),
 	}
 
-	allocCtx, cancel := chromedp.NewAllocator(context.Background(),
+	allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
-		chromedp.WithExecAllocator(opts...))
 	defer cancel()
 
 	taskCtx, cancel := chromedp.NewContext(allocCtx)