Native memory histograms for the browser.

content/browser/histogram_message_filter.cc

 // 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.
 
 #include "content/browser/histogram_message_filter.h"
 
+#include "base/command_line.h"
+#include "base/metrics/histogram.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/process_util.h"
 #include "content/browser/histogram_controller.h"
 #include "content/browser/tcmalloc_internals_request_job.h"
 #include "content/common/child_process_messages.h"
+#include "content/public/common/content_switches.h"
 
 namespace content {
 
 HistogramMessageFilter::HistogramMessageFilter() {}
 
 void HistogramMessageFilter::OnChannelConnected(int32 peer_pid) {
   BrowserMessageFilter::OnChannelConnected(peer_pid);
 }
 
 bool HistogramMessageFilter::OnMessageReceived(const IPC::Message& message,
                                               bool* message_was_ok) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP_EX(HistogramMessageFilter, message, *message_was_ok)
     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_ChildHistogramData,
                         OnChildHistogramData)
+    IPC_MESSAGE_HANDLER(ChildProcessHostMsg_GetBrowserHistogram,
+                        OnGetBrowserHistogram)

[jochen (gone - plz use gerrit), 2013/01/18 14:03:11]

you need to make sure that this is on the IO thread. we can't have sync ipcs on
the ui thread

[marja, 2013/01/18 15:00:08]

Added a dcheck in the handler func; it's run in the IO thread.

     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP_EX()
   return handled;
 }
 
 HistogramMessageFilter::~HistogramMessageFilter() {}
 
 void HistogramMessageFilter::OnChildHistogramData(
     int sequence_number,
     const std::vector<std::string>& pickled_histograms) {
   HistogramController::GetInstance()->OnHistogramDataCollected(
       sequence_number, pickled_histograms);
 }
+
+void HistogramMessageFilter::OnGetBrowserHistogram(
+    const std::string& name,
+    std::string* histogram_json) {
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kMemoryMetrics))
+    return;
+  base::Histogram* histogram =
+      base::StatisticsRecorder::FindHistogram(name);

[jochen (gone - plz use gerrit), 2013/01/18 14:03:11]

maybe even add a whitelist?

[marja, 2013/01/18 15:00:08]

Done.

+  if (!histogram) {
+    *histogram_json = "{}";
+  } else {
+    histogram->WriteJSON(histogram_json);
+  }
 }
+
+}

[jochen (gone - plz use gerrit), 2013/01/18 14:03:11]

// namespace content

[marja, 2013/01/18 15:00:08]

Done.