Split UserMetrics into API vs. implementation. Move API to content/public.

content/public/browser/user_metrics.h

 // Copyright (c) 2011 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.
 
-#ifndef CONTENT_BROWSER_USER_METRICS_H_
-#define CONTENT_BROWSER_USER_METRICS_H_
+#ifndef CONTENT_PUBLIC_BROWSER_USER_METRICS_H_
+#define CONTENT_PUBLIC_BROWSER_USER_METRICS_H_
 #pragma once
 
 #include <string>
 
 #include "content/common/content_export.h"
 
 // This module provides some helper functions for logging actions tracked by
 // the user metrics system.
+//
+// Note that we do not wrap this in the content namespace to avoid
+// making it more difficult to comply with the single-line requirement
+// discussed for UserMetrics::RecordAction below.
 
 
 // UserMetricsAction exist purely to standardize on the paramters passed to
 // UserMetrics. That way, our toolset can scan the sourcecode reliable for
 // constructors and extract the associated string constants
 struct UserMetricsAction {
   const char* str_;
   explicit UserMetricsAction(const char* str) : str_(str) {}
 };
 
 
 class CONTENT_EXPORT UserMetrics {

[jam, 2011/12/12 23:06:55]

it seems that we don't need the UserMetrics class for scoping now that we have a
content namespace. for other APIs, i've been removing such classes and putting
the static functions in the content namespace.

it's much easier to tell people that we have a simple rule (everything in the
content namespace, similar to WebKit namespace for the webkit API), rather than
to start making exceptions

  public:
   // Record that the user performed an action.
   // "Action" here means a user-generated event:
   //   good: "Reload", "CloseTab", and "IMEInvoked"
   //   not good: "SSLDialogShown", "PageLoaded", "DiskFull"
   // We use this to gather anonymized information about how users are
   // interacting with the browser.
   // WARNING: Call this function exactly like this:
   //   UserMetrics::RecordAction(UserMetricsAction("foo bar"));
   // (all on one line and with the metric string literal [no variables])
   // because otherwise our processing scripts won't pick up on new actions.
   //
   // Once a new recorded action is added, run chrome/tools/extract_actions.py
   // to generate a new mapping of [action hashes -> metric names] and send it
   // out for review to be updated.
   //
   // For more complicated situations (like when there are many different
   // possible actions), see RecordComputedAction.
   static void RecordAction(const UserMetricsAction& action);
 
   // This function has identical input and behavior to RecordAction, but is
   // not automatically found by the action-processing scripts.  It can be used
   // when it's a pain to enumerate all possible actions, but if you use this
   // you need to also update the rules for extracting known actions in
   // chrome/tools/extract_actions.py.
   static void RecordComputedAction(const std::string& action);
-
- private:
-  static void Record(const char *action);
-  static void CallRecordOnUI(const std::string& action);
 };
 
-#endif  // CONTENT_BROWSER_USER_METRICS_H_
+#endif  // CONTENT_PUBLIC_BROWSER_USER_METRICS_H_