oauth2: rename SetParam to SetAuthURLParam

SetParam is quite vague to represent an Option that sets the auth
URL query parameters. Renaming it for explicitness.

Fixes #108.

Change-Id: Ic9f0181097820ee83404c9432451d71658dd8c67
Reviewed-on: https://go-review.googlesource.com/8491
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/oauth2.go b/oauth2.go
index 0c6a1ed..98b3c2c 100644
--- a/oauth2.go
+++ b/oauth2.go
@@ -79,13 +79,13 @@
 	// result in your application obtaining a refresh token the
 	// first time your application exchanges an authorization
 	// code for a user.
-	AccessTypeOnline  AuthCodeOption = SetParam("access_type", "online")
-	AccessTypeOffline AuthCodeOption = SetParam("access_type", "offline")
+	AccessTypeOnline  AuthCodeOption = SetAuthURLParam("access_type", "online")
+	AccessTypeOffline AuthCodeOption = SetAuthURLParam("access_type", "offline")
 
 	// ApprovalForce forces the users to view the consent dialog
 	// and confirm the permissions request at the URL returned
 	// from AuthCodeURL, even if they've already done so.
-	ApprovalForce AuthCodeOption = SetParam("approval_prompt", "force")
+	ApprovalForce AuthCodeOption = SetAuthURLParam("approval_prompt", "force")
 )
 
 // An AuthCodeOption is passed to Config.AuthCodeURL.
@@ -97,9 +97,9 @@
 
 func (p setParam) setValue(m url.Values) { m.Set(p.k, p.v) }
 
-// SetParam builds an AuthCodeOption which passes key/value parameters
+// SetAuthURLParam builds an AuthCodeOption which passes key/value parameters
 // to a provider's authorization endpoint.
-func SetParam(key, value string) AuthCodeOption {
+func SetAuthURLParam(key, value string) AuthCodeOption {
 	return setParam{key, value}
 }
 
diff --git a/oauth2_test.go b/oauth2_test.go
index 0bc6129..7b7e3c1 100644
--- a/oauth2_test.go
+++ b/oauth2_test.go
@@ -63,7 +63,7 @@
 
 func TestAuthCodeURL_CustomParam(t *testing.T) {
 	conf := newConf("server")
-	param := SetParam("foo", "bar")
+	param := SetAuthURLParam("foo", "bar")
 	url := conf.AuthCodeURL("baz", param)
 	if url != "server/auth?client_id=CLIENT_ID&foo=bar&redirect_uri=REDIRECT_URL&response_type=code&scope=scope1+scope2&state=baz" {
 		t.Errorf("Auth code URL doesn't match the expected, found: %v", url)