DevTools: Simplify Page.captureScreenshot API (Blink side)

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 435 matching lines @@
                 "name": "setEmulatedMedia",
                 "parameters": [
                     { "name": "media", "type": "string", "description": "Media type to emulate. Empty string disables the override." }
                 ],
                 "description": "Emulates the given media for CSS media queries.",
                 "hidden": true
             },
             {
                 "name": "captureScreenshot",
                 "description": "Capture page screenshot.",
-                "parameters": [
-                    { "name": "format", "type": "string", "optional": true, "enum": ["jpeg", "png"], "description": "Image compression format." },
-                    { "name": "quality", "type": "integer", "hidden": true, "optional": true, "description": "Compression quality from range [0..100]." },
-                    { "name": "maxWidth", "type": "integer", "hidden": true, "optional": true, "description": "Maximum screenshot width." },
-                    { "name": "maxHeight", "type": "integer", "hidden": true, "optional": true, "description": "Maximum screenshot height." }
-                ],
+                "parameters": [],
                 "returns": [
-                    { "name": "data", "type": "string", "description": "Base64-encoded image data (PNG)." },
-                    { "name": "metadata", "$ref": "ScreencastFrameMetadata", "description": "Screencast frame metadata"}
+                    { "name": "data", "type": "string", "description": "Base64-encoded image data (PNG)." }
                 ],
                 "hidden": true,
                 "handlers": ["browser"]
             },
             {
                 "name": "canScreencast",
                 "description": "Tells whether screencast is supported.",
                 "returns": [
                   { "name": "result", "type": "boolean", "description": "True if screencast is supported." }
                 ],
@@ skipping 3589 matching lines @@
             {
                 "name": "dataAvailable",
                 "parameters": [
                     {"name": "value", "type": "array", "items": { "$ref": "PowerEvent" }, "description": "List of power events." }
                 ],
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }