Quota view in Resources pannel.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 166 matching lines @@
             {
                 "id": "NavigationEntry",
                 "type": "object",
                 "description": "Navigation history entry.",
                 "properties": [
                   { "name": "id", "type": "integer", "description": "Unique id of the navigation history entry." },
                   { "name": "url", "type": "string", "description": "URL of the navigation history entry." },
                   { "name": "title", "type": "string", "description": "Title of the navigation history entry." }
                 ],
                 "hidden": true
+            },
+            {
+                "id": "Quota",
+                "type": "object",
+                "description": "Quota information",
+                "properties": [
+                    { "name": "temporary", "type": "number", "description": "Quota for temporary storage shared among all security origins" },
+                    { "name": "persistent", "type": "number", "description": "Quota for persistent storage for the security origin." }
+                ],
+                "hidden": true
+            },
+            {
+                "id": "Usage",
+                "type": "object",
+                "description": "Usage information",
+                "properties": [
+                    { "name": "temporary", "type": "array", "items": { "$ref": "UsageItem" }, "description": "" },
+                    { "name": "persistent", "type": "array", "items": { "$ref": "UsageItem" }, "description": "" },
+                    { "name": "syncable", "type": "array", "items": { "$ref": "UsageItem" }, "description": "" }
+                ],
+                "hidden": true
+            },
+            {
+                "id": "UsageItem",
+                "type": "object",
+                "description": "Usage information for a client and storage type",
+                "properties": [
+                    { "name": "id", "type": "string", "enum": ["filesystem", "database", "appcache", "indexeddatabase"], "description": "" },
+                    { "name": "value", "type": "number", "description": "" }
+                ],
+                "hidden": true
             }
         ],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables page domain notifications."
             },
             {
                 "name": "disable",
                 "description": "Disables page domain notifications."
@@ skipping 283 matching lines @@
                 ],
                 "hidden": true
             },
             {
                 "name": "setForceCompositingMode",
                 "description": "Force accelerated compositing mode for inspected page.",
                 "parameters": [
                     { "name": "force", "type": "boolean", "description": "Whether to force accelerated compositing or not." }
                 ],
                 "hidden": true
+            },
+            {
+                "name": "queryUsageAndQuota",
+                "description": ".",
+                "parameters": [
+                    { "name": "securityOrigin", "type": "string", "description": "Securicy origin quota and usage requested for" }
+                ],
+                "returns": [
+                    {
+                        "name": "quota",
+                        "$ref": "Quota"
+                    },
+                    {
+                        "name": "usage",
+                        "$ref": "Usage"
+                    }
+                ],
+                "description": "Queries more detailed quota nad usage data than Storage API provides.",
+                "hidden": true
             }
         ],
         "events": [
             {
                 "name": "domContentEventFired",
                 "parameters": [
                     { "name": "timestamp", "type": "number" }
                 ]
             },
             {
@@ skipping 3541 matching lines @@
                 "parameters": [
                     { "name": "value", "type": "array", "items": { "type": "object" } }
                 ]
             },
             {
                 "name": "tracingComplete"
             }
         ]
     }]
 }