Refactor the implementation of the webNavigation extension API.

chrome/common/extensions/api/web_navigation.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "webNavigation",
     "description": "Use the <code>chrome.webNavigation</code> API to receive notifications about the status of navigation requests in-flight.",
     "types": [
       {
@@ skipping 119 matching lines @@
             "description": "Conditions that the URL being navigated to must satisfy. The 'schemes' and 'ports' fields of UrlFilter are ignored for this event."
           }
         ],
         "parameters": [
           {
             "type": "object",
             "name": "details",
             "properties": {
               "tabId": {"type": "integer", "description": "The ID of the tab in which the navigation is about to occur."},
               "url": {"type": "string"},
-              "processId": {"type": "integer", "description": "The ID of the process that runs the renderer for this frame."},
+              "processId": {"type": "integer", "description": "The value of -1, since the process which will render the resulting document is not known until onCommit."},

[Devlin, 2016/02/09 17:35:40]

I'd phrase this to include "deprecated" so it's clear that we're not just
passing -1 for funzies.  There's even a "deprecated" key - see e.g. line 37.

[nasko, 2016/02/09 17:53:54]

Done.

               "frameId": {"type": "integer", "description": "0 indicates the navigation happens in the tab content window; a positive value indicates navigation in a subframe. Frame IDs are unique for a given tab and process."},
               "parentFrameId": {"type": "integer", "description": "ID of frame that wraps the frame. Set to -1 of no parent frame exists."},
               "timeStamp": {"type": "number", "description": "The time when the browser was about to start the navigation, in milliseconds since the epoch."}
             }
           }
         ]
       },
       {
         "name": "onCommitted",
         "type": "function",
@@ skipping 86 matching lines @@
             "description": "Conditions that the URL being navigated to must satisfy. The 'schemes' and 'ports' fields of UrlFilter are ignored for this event."
           }
         ],
         "parameters": [
           {
             "type": "object",
             "name": "details",
             "properties": {
               "tabId": {"type": "integer", "description": "The ID of the tab in which the navigation occurs."},
               "url": {"type": "string"},
-              "processId": {"type": "integer", "description": "The ID of the process that runs the renderer for this frame."},
+              "processId": {"type": "integer", "description": "The value of -1."},

[Devlin, 2016/02/09 17:35:40]

ditto.  We also don't object to copy-pasting in docs, because they're more
likely to be used as quick references than detailed reading, so don't assume
people read the above entries.

[nasko, 2016/02/09 17:53:54]

Done.

               "frameId": {"type": "integer", "description": "0 indicates the navigation happens in the tab content window; a positive value indicates navigation in a subframe. Frame IDs are unique within a tab."},
               "error": {"type": "string", "description": "The error description."},
               "timeStamp": {"type": "number", "description": "The time when the error occurred, in milliseconds since the epoch."}
             }
           }
         ]
       },
       {
         "name": "onCreatedNavigationTarget",
         "type": "function",
@@ skipping 89 matching lines @@
               "transitionType": {"$ref": "TransitionType", "description": "Cause of the navigation."},
               "transitionQualifiers": {"type": "array", "description": "A list of transition qualifiers.", "items": {"$ref": "TransitionQualifier"}},
               "timeStamp": {"type": "number", "description": "The time when the navigation was committed, in milliseconds since the epoch."}
             }
           }
         ]
       }
     ]
   }
 ]