NTP: Clean up of MetricsHandler class and namespacing chrome.send messages.

chrome/browser/ui/webui/ntp/metrics_handler.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 CHROME_BROWSER_UI_WEBUI_NTP_METRICS_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_NTP_METRICS_HANDLER_H_
+
+#include "content/browser/webui/web_ui.h"
+
+///////////////////////////////////////////////////////////////////////////////
+// MetricsHandler
+
+// Let the page contents record UMA actions. Only use when you can't do it from
+// C++. For example, we currently use it to let the NTP log the postion of the
+// Most Visited or Bookmark the user clicked on, as we don't get that
+// information through RequestOpenURL. You will need to update the metrics
+// dashboard with the action names you use, as our processor won't catch that
+// information (treat it as RecordComputedMetrics)
+
+namespace base {
+class ListValue;
+}
+
+class MetricsHandler : public WebUIMessageHandler {
+ public:
+  MetricsHandler();
+  virtual ~MetricsHandler();
+
+  // WebUIMessageHandler implementation.
+  virtual void RegisterMessages() OVERRIDE;
+
+  // Callback for the "metricsHandler:recordAction" message. This records a
+  // user action.
+  void HandleRecordAction(const base::ListValue* args);
+
+  // Callback for the "metricsHandler:recordInHistogram" message. This records
+  // into a histogram. |args| contains the histogram name, the value to record,
+  // and the maximum allowed value, which can be at most 4000. The histogram
+  // will use at most 100 buckets, one for each 1, 10, or 100 different values,
+  // depending on the maximum value.
+  void HandleRecordInHistogram(const base::ListValue* args);
+
+  // Callback for the "metricsHandler:logEventTime" message.
+  void HandleLogEventTime(const base::ListValue* args);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MetricsHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_NTP_METRICS_HANDLER_H_