Add Origin Power Map to Store Battery Auditing Data.

components/power/origin_power_map.cc

Index: components/power/origin_power_map.cc
diff --git a/components/power/origin_power_map.cc b/components/power/origin_power_map.cc
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index 0000000000000000000000000000000000000000..e356173373a284a7dbf7159e6533fa48d58c4bb3
--- /dev/null
+++ b/components/power/origin_power_map.cc
@@ -0,0 +1,49 @@
+// Copyright 2014 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 "components/power/origin_power_map.h"
+
+#include "base/logging.h"
+#include "url/gurl.h"
+
+// Hardcode to avoid dependency on //content.
+const char kChromeUIScheme[] = "chrome";

[Daniel Erat, 2014/08/12 15:58:52]

duplicating a constant to avoid a dependency feels gross. do any other things
outside of content/ need to deal with this?

[Daniel Nishi, 2014/08/12 17:33:46]

There is precedent to avoid dependencies on //content to duplicate constants,
however since we're not on iOS and have a content dependency already I've
changed this back to using the regular constant.

+
+namespace power {
+
+OriginPowerMap::OriginPowerMap() : total_consumed_() {

[Daniel Erat, 2014/08/12 15:58:52]

explicitly initialize |total_consumed_| to 0.0

[Daniel Nishi, 2014/08/12 17:33:46]

Done.

+}
+
+OriginPowerMap::~OriginPowerMap() {
+}
+
+int OriginPowerMap::GetPowerForOrigin(const GURL& url) {
+  GURL origin = url.GetOrigin();
+  if (origin_map_.find(origin) == origin_map_.end() || !total_consumed_)
+    return 0;
+  return origin_map_[origin] * 100 / total_consumed_;

[Daniel Erat, 2014/08/12 15:58:52]

use an iterator so you don't do the lookup twice.

might as well also skip the lookup if total_consumed_ is 0.

and you should probably round the result, right?

  if (!total_consumed_)
    return 0;

  OriginMap::const_iterator it = origin_map_.find(origin);
  return it == origin_map_.end() ? 0 :
      static_cast<int>(it->second * 100 / total_consumed_ + 0.5);

[Daniel Nishi, 2014/08/12 17:33:46]

Done.

+}
+
+void OriginPowerMap::AddPowerForOrigin(const GURL& url, double power) {
+  DCHECK_GE(power, 0);
+  GURL origin = url.GetOrigin();
+  if (!origin.is_valid() || origin.SchemeIs(kChromeUIScheme))
+    return;
+
+  origin_map_[origin] += power;
+  total_consumed_ += power;
+}
+
+scoped_ptr<OriginPowerMap::PercentOriginMap>
+OriginPowerMap::GetPercentOriginMap() {
+  scoped_ptr<OriginPowerMap::PercentOriginMap> percent_map(
+      new OriginPowerMap::PercentOriginMap);
+  for (OriginMap::iterator it = origin_map_.begin(); it != origin_map_.end();
+       ++it) {

[Daniel Erat, 2014/08/12 15:58:52]

don't you need to return here if total_consumed_ is 0 to avoid a divide-by-zero,
as in GetPowerForOrigin()? please add a test for this.

[Daniel Nishi, 2014/08/12 17:33:46]

This is true.

If all sources in the map consumed no power, it's effectively like saying
nothing did, so I've added a return of an empty map here.

+    (*percent_map)[it->first] = (it->second / total_consumed_ * 100);

[Daniel Erat, 2014/08/12 15:58:52]

round here too

[Daniel Nishi, 2014/08/12 17:33:46]

Done.

+  }
+  return percent_map.Pass();
+}
+
+}  // namespace power