Add metrics for DHCP WPAD feature. Fix memory overwrite.

BUG=18575
TEST=net_unittests

Review URL: http://codereview.chromium.org/6975027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@86421 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 27 insertions, 1 deletions

diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index 4262853..6fd30be 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -940,6 +940,21 @@ Histogram::ClassType CustomHistogram::histogram_type() const {
   return CUSTOM_HISTOGRAM;
 }
 
+// static
+std::vector<Histogram::Sample> CustomHistogram::ArrayToCustomRanges(
+    const Sample* values, size_t num_values) {
+  std::vector<Sample> all_values;
+  for (size_t i = 0; i < num_values; ++i) {
+    Sample value = values[i];
+    all_values.push_back(value);
+
+    // Ensure that a guard bucket is added. If we end up with duplicate
+    // values, FactoryGet will take care of removing them.
+    all_values.push_back(value + 1);
+  }
+  return all_values;
+}
+
 CustomHistogram::CustomHistogram(const std::string& name,
                                  const std::vector<Sample>& custom_ranges)
     : Histogram(name, custom_ranges[1], custom_ranges.back(),
diff --git a/base/metrics/histogram.h b/base/metrics/histogram.h
index bc58ee5..29004e4 100644
--- a/base/metrics/histogram.h
+++ b/base/metrics/histogram.h
@@ -108,7 +108,6 @@ class Lock;
 
 // Support histograming of an enumerated value.  The samples should always be
 // less than boundary_value.
-
 #define HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
     static base::Histogram* counter(NULL); \
     if (!counter) \
@@ -118,6 +117,10 @@ class Lock;
     counter->Add(sample); \
   } while (0)
 
+// Support histograming of an enumerated value. Samples should be one of the
+// std::vector<int> list provided via |custom_ranges|. You can use the helper
+// function |base::CustomHistogram::ArrayToCustomRanges(samples, num_samples)|
+// to transform a C-style array of valid sample values to a std::vector<int>.
 #define HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) do { \
     static base::Histogram* counter(NULL); \
     if (!counter) \
@@ -664,6 +667,14 @@ class BASE_API CustomHistogram : public Histogram {
   // Overridden from Histogram:
   virtual ClassType histogram_type() const;
 
+  // Helper method for transforming an array of valid enumeration values
+  // to the std::vector<int> expected by HISTOGRAM_CUSTOM_ENUMERATION.
+  // This function ensures that a guard bucket exists right after any
+  // valid sample value (unless the next higher sample is also a valid value),
+  // so that invalid samples never fall into the same bucket as valid samples.
+  static std::vector<Sample> ArrayToCustomRanges(const Sample* values,
+                                                 size_t num_values);
+
  protected:
   CustomHistogram(const std::string& name,
                   const std::vector<Sample>& custom_ranges);