[devtools] Support different encodings for Page.CaptureScreenshot.

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

Index: third_party/WebKit/Source/core/inspector/browser_protocol.json
diff --git a/third_party/WebKit/Source/core/inspector/browser_protocol.json b/third_party/WebKit/Source/core/inspector/browser_protocol.json
index 8c02d78c3780558feed84f98051937a7f1431215..738228153768d44ff3eb166731351855c8f60282 100644
--- a/third_party/WebKit/Source/core/inspector/browser_protocol.json
+++ b/third_party/WebKit/Source/core/inspector/browser_protocol.json
@@ -416,8 +416,12 @@
             {
                 "name": "captureScreenshot",
                 "description": "Capture page screenshot.",
+                "parameters": [
+                    { "name": "format", "type": "string", "optional": true, "enum": ["jpeg", "png"], "description": "Image compression format (defaults to png)." },
+                    { "name": "quality", "type": "integer", "optional": true, "description": "Compression quality from range [0..100] (jpeg only)." }
+                ],
                 "returns": [
-                    { "name": "data", "type": "string", "description": "Base64-encoded image data (PNG)." }
+                    { "name": "data", "type": "string", "description": "Base64-encoded image data." }
                 ],
                 "experimental": true
             },