Initial import of the Chrome Frame codebase. Integration in chrome.gyp coming...

chrome_frame/chrome_frame_histograms.cc

Index: chrome_frame/chrome_frame_histograms.cc
===================================================================
--- chrome_frame/chrome_frame_histograms.cc	(revision 0)
+++ chrome_frame/chrome_frame_histograms.cc	(revision 0)
@@ -0,0 +1,81 @@
+// Copyright (c) 2009 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 "chrome_frame/chrome_frame_histograms.h"
+
+#include "base/histogram.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/pickle.h"
+
+  // Initialize histogram statistics gathering system.
+base::LazyInstance<StatisticsRecorder>
+    g_statistics_recorder_(base::LINKER_INITIALIZED);
+
+ChromeFrameHistogramSnapshots::ChromeFrameHistogramSnapshots() {
+  // Ensure that an instance of the StatisticsRecorder object is created.
+  g_statistics_recorder_.Get();
+}
+
+ChromeFrameHistogramSnapshots::HistogramPickledList
+  ChromeFrameHistogramSnapshots::GatherAllHistograms() {
+
+  StatisticsRecorder::Histograms histograms;
+  StatisticsRecorder::GetHistograms(&histograms);
+
+  HistogramPickledList pickled_histograms;
+
+  for (StatisticsRecorder::Histograms::iterator it = histograms.begin();
+       histograms.end() != it;
+       it++) {
+    GatherHistogram(**it, &pickled_histograms);
+  }
+
+  return pickled_histograms;
+}
+
+void ChromeFrameHistogramSnapshots::GatherHistogram(
+    const Histogram& histogram,
+    HistogramPickledList* pickled_histograms) {
+
+  // Get up-to-date snapshot of sample stats.
+  Histogram::SampleSet snapshot;
+  histogram.SnapshotSample(&snapshot);
+  const std::string& histogram_name = histogram.histogram_name();
+
+  // Check if we already have a log of this histogram and if not create an
+  // empty set.
+  LoggedSampleMap::iterator it = logged_samples_.find(histogram_name);
+  Histogram::SampleSet* already_logged;
+  if (logged_samples_.end() == it) {
+    // Add new entry.
+    already_logged = &logged_samples_[histogram.histogram_name()];
+    already_logged->Resize(histogram);  // Complete initialization.
+  } else {
+    already_logged = &(it->second);
+    // Deduct any stats we've already logged from our snapshot.
+    snapshot.Subtract(*already_logged);
+  }
+
+  // Snapshot now contains only a delta to what we've already_logged.
+  if (snapshot.TotalCount() > 0) {
+    GatherHistogramDelta(histogram, snapshot, pickled_histograms);
+    // Add new data into our running total.
+    already_logged->Add(snapshot);
+  }
+}
+
+void ChromeFrameHistogramSnapshots::GatherHistogramDelta(
+    const Histogram& histogram,
+    const Histogram::SampleSet& snapshot,
+    HistogramPickledList* pickled_histograms) {
+
+  DCHECK(0 != snapshot.TotalCount());
+  snapshot.CheckSize(histogram);
+
+  std::string histogram_info =
+      Histogram::SerializeHistogramInfo(histogram, snapshot);
+  pickled_histograms->push_back(histogram_info);
+}