Move the "extension" namespace from extension_api.json into extension_api_extension.json.

chrome/common/extensions/docs/samples.json

 {
   "api": {
     "chrome.bookmarks.create": "bookmarks.html#method-create",
     "chrome.bookmarks.export": "bookmarks.html#method-export",
     "chrome.bookmarks.get": "bookmarks.html#method-get",
     "chrome.bookmarks.getChildren": "bookmarks.html#method-getChildren",
     "chrome.bookmarks.getRecent": "bookmarks.html#method-getRecent",
     "chrome.bookmarks.getSubTree": "bookmarks.html#method-getSubTree",
     "chrome.bookmarks.getTree": "bookmarks.html#method-getTree",
     "chrome.bookmarks.import": "bookmarks.html#method-import",
@@ skipping 844 matching lines @@
         "analytics.js",
         "background.html",
         "manifest.json",
         "popup.html"
       ],
       "source_hash": "b02f040a3eb56f8a0e780549954f69172d62dcd3",
       "zip_path": "examples\/tutorials\/analytics.zip"
     },
     {
       "api_calls": [
-        "chrome.omnibox.onInputChanged",
-        "chrome.omnibox.onInputEntered",
-        "chrome.tabs.create",
-        "chrome.tabs.get",
-        "chrome.tabs.onRemoved",
-        "chrome.tabs.update"
-      ],
-      "crx_path": null,
-      "description": "Search the Chrome Extensions documentation.  To use, type 'crdoc' plus a search term into the Omnibox.",
-      "features": [
-        "background_page",
-        "tabs"
-      ],
-      "icon": "icon-128.png",
-      "id": "e3df888a89e35bdeb9c8bc8d03be5e1851b97c68",
-      "name": "Extension Docs Search",
-      "packaged_app": false,
-      "path": "examples\/api\/omnibox\/extension-docs\/",
-      "protocols": [
-        "https:\/\/"
-      ],
-      "search_string": "EXTENSION DOCS SEARCH SEARCH THE CHROME EXTENSIONS DOCUMENTATION.  TO USE, TYPE CRDOC PLUS A SEARCH TERM INTO THE OMNIBOX. BACKGROUND_PAGE TABS CHROME.OMNIBOX.ONINPUTCHANGED CHROME.OMNIBOX.ONINPUTENTERED CHROME.TABS.CREATE CHROME.TABS.GET CHROME.TABS.ONREMOVED CHROME.TABS.UPDATE",
-      "source_files": [
-        "background.html",
-        "background.js",
-        "manifest.json"
-      ],
-      "source_hash": "c294cbd813e4a59b3ee8270892f10c68aa3f53b3",
-      "zip_path": "examples\/api\/omnibox\/extension-docs.zip"
-    },
-    {
-      "api_calls": [
         "chrome.experimental.devtools.network.getHAR",
         "chrome.experimental.devtools.network.onRequestFinished",
         "chrome.extension.onRequest",
         "chrome.extension.sendRequest",
         "chrome.tabs.executeScript"
       ],
       "crx_path": null,
       "description": "Extends the Developer Tools, adding support for parsing FirePHP messages from server",
       "features": [
         "background_page",
@@ skipping 1564 matching lines @@
         "manifest.json",
         "popup.html",
         "popup.js",
         "sample.css"
       ],
       "source_hash": "62ca453d8d1551ff63dd7c78b49d546bc3af17c6",
       "zip_path": "examples\/api\/extension\/isAllowedAccess.zip"
     }
   ]
 }