Add a metrics extensions API....

chrome/common/extensions/api/extension_api.json

Index: chrome/common/extensions/api/extension_api.json
===================================================================
--- chrome/common/extensions/api/extension_api.json	(revision 40111)
+++ chrome/common/extensions/api/extension_api.json	(working copy)
@@ -2256,6 +2256,111 @@
     "events": []
   },
   {
+    "namespace": "metrics",
+    "types": [
+      {
+        "id": "MetricType",
+        "type":  "object",
+        "description": "Describes the type of metric that is to be collected.",
+        "properties": {
+          "metricName": {"type": "string", "description": "A unique name within the extension for the metric."},
+          "type": {
+            "type": "string",
+            "enum": ["histogram-log", "histogram-linear"],
+            "description": "The type of metric, such as 'histogram-log' or 'histogram-linear'."
+          },
+          "min": {"type": "integer", "description": "The minimum sample value to be recoded.  Must be greater than zero."},
+          "max": {"type": "integer", "description": "The maximum sample value to be recoded."},
+          "buckets": {"type": "integer", "description": "The number of buckets to use when separating the recorded values."}
+        }
+      }
+    ],
+    "functions": [
+      {
+        "name": "recordUserAction",
+        "type": "function",
+        "description": "Records an action performed by the user.",
+        "parameters": [
+          {"name": "name", "type": "string"}
+        ]
+      },
+      {
+        "name": "recordPercentage",
+        "type": "function",
+        "description": "Record a percentage value from 1 to 100.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordCount",
+        "type": "function",
+        "description": "Record a value than can range from 1 to 1,000,000.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordSmallCount",
+        "type": "function",
+        "description": "Record a value than can range from 1 to 100.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordMediumCount",
+        "type": "function",
+        "description": "Record a value than can range from 1 to 10,000.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordTime",
+        "type": "function",
+        "description": "Record an elapsed time of no more than 10 seconds.  The sample value is specified in milliseconds.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordMediumTime",
+        "type": "function",
+        "description": "Record an elapsed time of no more than 3 minutes.  The sample value is specified in milliseconds.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordLongTime",
+        "type": "function",
+        "description": "Record an elapsed time of no more than 1 hour.  The sample value is specified in milliseconds.",
+        "parameters": [
+          {"name": "metricName", "type": "string"},
+          {"name": "value", "type": "integer"}
+        ]
+      },
+      {
+        "name": "recordValue",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Adds a value to the given metric.",
+        "parameters": [
+          {"name": "metric", "$ref": "MetricType"},
+          {"name": "value", "type": "integer"}
+        ]
+      }
+    ],
+    "events": []
+  },
+  {
     "namespace": "test",
     "nodoc": true,
     "types": [],