Adds scroll position/scale emulation to DevTools.

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 92da94fe533f82d51308b740d9fe1a991129fdd4..df48350d838adb4a2b0e9bdb466b8e2c0ed09bbf 100644
--- a/third_party/WebKit/Source/core/inspector/browser_protocol.json
+++ b/third_party/WebKit/Source/core/inspector/browser_protocol.json
@@ -675,7 +675,7 @@
         "commands": [
             {
                 "name": "setDeviceMetricsOverride",
-                "description": "Overrides the values of device screen dimensions (window.screen.width, window.screen.height, window.innerWidth, window.innerHeight, and \"device-width\"/\"device-height\"-related CSS media query results).",
+                "description": "Overrides the values of device, screen, and viewport dimensions and positions (including window.screen.width, window.screen.height, window.innerWidth, window.innerHeight, and \"device-width\"/\"device-height\"-related CSS media query results).",
                 "parameters": [
                     { "name": "width", "type": "integer", "description": "Overriding width value in pixels (minimum 0, maximum 10000000). 0 disables the override." },
                     { "name": "height", "type": "integer", "description": "Overriding height value in pixels (minimum 0, maximum 10000000). 0 disables the override." },
@@ -689,7 +689,14 @@
                     { "name": "screenHeight", "type": "integer", "optional": true, "description": "Overriding screen height value in pixels (minimum 0, maximum 10000000). Only used for |mobile==true|." },
                     { "name": "positionX", "type": "integer", "optional": true, "description": "Overriding view X position on screen in pixels (minimum 0, maximum 10000000). Only used for |mobile==true|." },
                     { "name": "positionY", "type": "integer", "optional": true, "description": "Overriding view Y position on screen in pixels (minimum 0, maximum 10000000). Only used for |mobile==true|." },
-                    { "name": "screenOrientation", "$ref": "ScreenOrientation", "optional": true, "description": "Screen orientation override." }
+                    { "name": "screenOrientation", "$ref": "ScreenOrientation", "optional": true, "description": "Screen orientation override." },
+                    { "name": "scrollPositionX", "type": "integer", "optional": true, "description": "Fix horizontal scroll position of outer viewport (frame) to an override value (device-independent pixel)." },

[bokan, 2016/07/04 22:44:09]

The `outer`/`inner` terminology is specific to the compositor. Outside it we
just use `layout` and `visual`.

[Eric Seckler, 2016/07/05 16:46:51]

Done, also in WebDeviceEmulationParams.

+                    { "name": "scrollPositionY", "type": "integer", "optional": true, "description": "Fix  vertical scroll position of outer viewport (frame) to an override value (device-independent pixel)." },
+                    { "name": "visualViewportWidth", "type": "integer", "optional": true, "description": "Override height of inner (visual) viewport (pixels, minimum 0, maximum 10000000). Optional, defaults to |width|." },
+                    { "name": "visualViewportHeight", "type": "integer", "optional": true, "description": "Override height of inner (visual) viewport (pixels, minimum 0, maximum 10000000). Optional, defaults to |height|." },
+                    { "name": "visualViewportPositionX", "type": "number", "optional": true, "description": "Fix horizontal scroll position of inner (visual) viewport to an override value (partial device-independent pixels, relative to |scrollPositionX|)." },
+                    { "name": "visualViewportPositionY", "type": "number", "optional": true, "description": "Fix vertical scroll position of inner (visual) viewport to an override value (partial device-independent pixels, relative to |scrollPositionY|)." },
+                    { "name": "visualViewportScale", "type": "number", "optional": true, "description": "Fix pinch-zoom scale of the inner (visual) viewport to an override value (0 < value <= 10.0, 1.0 is default-scale)." }
                 ],
                 "handlers": ["browser"]
             },