add customized printing setting for headless

third_party/WebKit/Source/core/inspector/browser_protocol.json

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [{
         "domain": "Inspector",
         "experimental": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 411 matching lines @@
                     { "name": "quality", "type": "integer", "optional": true, "description": "Compression quality from range [0..100] (jpeg only)." },
                     { "name": "fromSurface", "type": "boolean", "optional": true, "description": "Capture the screenshot from the surface, rather than the view. Defaults to false.", "experimental": true }
                 ],
                 "returns": [
                     { "name": "data", "type": "string", "description": "Base64-encoded image data." }
                 ],
                 "experimental": true
             },
             {
                 "name": "printToPDF",
-                "description": "Print page as pdf.",
+                "description": "Print page as PDF.",
+                "parameters": [
+                    {"name": "landscape", "type": "boolean", "optional": true, "description": "Paper orientation. Defaults to false."},
+                    {"name": "displayHeaderFooter", "type": "boolean", "optional": true, "description": "Display header and footer. Defaults to false."},
+                    {"name": "printBackground", "type": "boolean", "optional": true, "description": "Print background graphics. Defaults to false."},
+                    {"name": "scale", "type": "number", "optional": true, "description": "Scale of the webpage rendering. Defaults to 1."},
+                    {"name": "paperWidth", "type": "number", "optional": true, "description": "Paper width in inches. Defaults to 8.5 inches."},
+                    {"name": "paperHeight", "type": "number", "optional": true, "description": "Paper height in inches. Defaults to 11 inches."},
+                    {"name": "marginTop", "type": "number", "optional": true, "description": "Top margin in inches. Defaults to 1cm (~0.4 inches)."},
+                    {"name": "marginBottom", "type": "number", "optional": true, "description": "Bottom margin in inches. Defaults to 1cm (~0.4 inches)."},
+                    {"name": "marginLeft", "type": "number", "optional": true, "description": "Left margin in inches. Defaults to 1cm (~0.4 inches)."},
+                    {"name": "marginRight", "type": "number", "optional": true, "description": "Right margin in inches. Defaults to 1cm (~0.4 inches)."},
+                    {"name": "pageRanges", "type": "string", "optional": true, "description": "Paper ranges to print, e.g., '1-5, 8, 11-13'. Defaults to the empty string, which means print all pages."}
+                ],
                 "returns": [
                     { "name": "data", "type": "string", "description": "Base64-encoded pdf data." }
                 ],
                 "experimental": true
             },
             {
                 "name": "startScreencast",
                 "description": "Starts sending each frame using the <code>screencastFrame</code> event.",
                 "parameters": [
                     { "name": "format", "type": "string", "optional": true, "enum": ["jpeg", "png"], "description": "Image compression format." },
@@ skipping 4206 matching lines @@
                 "parameters": [
                     { "name": "windowId", "$ref": "WindowID", "description": "Browser window id." }
                 ],
                 "returns": [
                     { "name": "bounds", "$ref": "Bounds", "description": "Bounds information of the window. When window state is 'minimized', the restored window position and size are returned." }
                 ]
             }
         ]
     }]
 }