Add /print command to web driver

go.mod

@@ -13,4 +13,4 @@ require (
 	github.com/google/go-github/v27 v27.0.4
 	github.com/mediabuyerbot/go-crx3 v1.3.1
 	google.golang.org/api v0.7.0
-)
+)

go.sum

@@ -46,7 +46,6 @@ github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfb
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.3.1/go.mod h1:sBzyDLLjw3U8JLTeZvSv8jJB+tU5PVekmnlKIyFUx0Y=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
-github.com/golang/protobuf v1.3.1 h1:YF8+flBXS5eO826T4nzqPrxfhQThhXl0YzfuUPu4SBg=
 github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.4 h1:87PNWwrRvUSnqS4dlcBU/ftvOIBep4sYuBLlh6rX2wk=
 github.com/golang/protobuf v1.3.4/go.mod h1:vzj43D7+SQXF/4pzW/hwtAqwc6iTitCiVSaWz5lYuqw=

remote.go

@@ -1282,6 +1282,41 @@ func (wd *remoteWD) Screenshot() ([]byte, error) {
 	return ioutil.ReadAll(decoder)
 }
 
+func (wd *remoteWD) Print(args PrintArgs) ([]byte, error) {
+	data, err := wd.stringPostCommand("/session/%s/print", args)
+	if err != nil {
+		return nil, err
+	}
+
+	// Selenium returns a base64 encoded image.
+	buf := []byte(data)
+	decoder := base64.NewDecoder(base64.StdEncoding, bytes.NewBuffer(buf))
+	return ioutil.ReadAll(decoder)
+}
+
+func (wd *remoteWD) stringPostCommand(urlTemplate string, params interface{}) (string, error) {
+	url := wd.requestURL(urlTemplate, wd.id)
+	bts, err := json.Marshal(params)
+	if err != nil {
+		return "", err
+	}
+	response, err := wd.execute("POST", url, bts)
+	if err != nil {
+		return "", err
+	}
+
+	reply := new(struct{ Value *string })
+	if err := json.Unmarshal(response, reply); err != nil {
+		return "", err
+	}
+
+	if reply.Value == nil {
+		return "", fmt.Errorf("nil return value")
+	}
+
+	return *reply.Value, nil
+}
+
 // Condition is an alias for a type that is passed as an argument
 // for selenium.Wait(cond Condition) (error) function.
 type Condition func(wd WebDriver) (bool, error)

selenium.go

@@ -255,6 +255,22 @@ type PointerAction map[string]interface{}
 // Actions stores KeyActions and PointerActions for later execution.
 type Actions []map[string]interface{}
 
+// PrintArgs specify the arguments that can
+// be sent to the Print() command.
+type PrintArgs struct {
+	Scale      float64  `json:"scale,omitempty"`
+	PageRanges []string `json:"pageRanges,omitempty"`
+	Margin     *Margin  `json:"margin,omitempty"`
+}
+
+// Margin for the print command.
+type Margin struct {
+	Bottom int `json:"bottom"`
+	Left   int `json:"left"`
+	Right  int `json:"right"`
+	Top    int `json:"top"`
+}
+
 // WebDriver defines methods supported by WebDriver drivers.
 type WebDriver interface {
 	// Status returns various pieces of information about the server environment.
@@ -396,6 +412,8 @@ type WebDriver interface {
 	KeyUp(keys string) error
 	// Screenshot takes a screenshot of the browser window.
 	Screenshot() ([]byte, error)
+	// Print takes PrintArgs and returns a PDF representation of the browser window.
+	Print(args PrintArgs) ([]byte, error)
 	// Log fetches the logs. Log types must be previously configured in the
 	// capabilities.
 	//