devtools: Adds Page.getLayoutMetrics.

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 165 matching lines @@
                   { "name": "column", "type": "integer", "description": "Error column." }
                 ],
                 "experimental": true
             },
             {
                 "id": "NavigationResponse",
                 "description": "Proceed: allow the navigation; Cancel: cancel the navigation; CancelAndIgnore: cancels the navigation and makes the requester of the navigation acts like the request was never made.",
                 "type": "string",
                 "enum": ["Proceed", "Cancel", "CancelAndIgnore"],
                 "experimental": true
+            },
+            {
+                "id": "LayoutViewport",
+                "type": "object",
+                "description": "Layout viewport position and dimensions.",
+                "experimental": true,
+                "properties": [
+                    { "name": "pageX", "type": "integer", "description": "Horizontal offset relative to the document (CSS pixels)." },
+                    { "name": "pageY", "type": "integer", "description": "Vertical offset relative to the document (CSS pixels)." },
+                    { "name": "clientWidth", "type": "integer", "description": "Width (CSS pixels), excludes scrollbar if present." },
+                    { "name": "clientHeight", "type": "integer", "description": "Height (CSS pixels), excludes scrollbar if present." }
+                ]
+            },
+            {
+                "id": "VisualViewport",
+                "type": "object",
+                "description": "Visual viewport position, dimensions, and scale.",
+                "experimental": true,
+                "properties": [
+                    { "name": "offsetX", "type": "number", "description": "Horizontal offset relative to the layout viewport (CSS pixels)." },
+                    { "name": "offsetY", "type": "number", "description": "Vertical offset relative to the layout viewport (CSS pixels)." },
+                    { "name": "pageX", "type": "number", "description": "Horizontal offset relative to the document (CSS pixels)." },
+                    { "name": "pageY", "type": "number", "description": "Vertical offset relative to the document (CSS pixels)." },
+                    { "name": "clientWidth", "type": "number", "description": "Width (CSS pixels), excludes scrollbar if present." },
+                    { "name": "clientHeight", "type": "number", "description": "Height (CSS pixels), excludes scrollbar if present." },
+                    { "name": "scale", "type": "number", "description": "Scale relative to the ideal viewport (size at width=device-width)." }
+                ]
             }
         ],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables page domain notifications.",
                 "handlers": ["browser", "renderer"]
             },
             {
                 "name": "disable",
@@ skipping 306 matching lines @@
             },
             {
                 "name": "processNavigation",
                 "parameters": [
                     { "name": "response", "$ref": "NavigationResponse" },
                     { "name": "navigationId", "type": "integer" }
                 ],
                 "description": "Should be sent in response to a navigationRequested or a redirectRequested event, telling the browser how to handle the navigation.",
                 "experimental": true,
                 "handlers": ["browser"]
+            },
+            {
+                "name": "getLayoutMetrics",
+                "description": "Returns metrics relating to the layouting of the page, such as viewport bounds/scale.",
+                "experimental": true,
+                "returns": [
+                    { "name": "layoutViewport", "$ref": "LayoutViewport", "description": "Metrics relating to the layout viewport." },
+                    { "name": "visualViewport", "$ref": "VisualViewport", "description": "Metrics relating to the visual viewport." }
+                ]
             }
         ],
         "events": [
             {
                 "name": "domContentEventFired",
                 "parameters": [
                     { "name": "timestamp", "type": "number" }
                 ]
             },
             {
@@ skipping 4133 matching lines @@
                 "description": "Informs that port was successfully bound and got a specified connection id.",
                 "parameters": [
                     {"name": "port", "type": "integer", "description": "Port number that was successfully bound." },
                     {"name": "connectionId", "type": "string", "description": "Connection id to be used." }
                 ],
                 "handlers": ["browser"]
             }
         ]
     }]
 }