libchrome: Several upstreamable fixes from libchrome

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index 3571657513f6482c5724f721c17e8a2c354ab79a..8180e3c11f157c56f4a9c82ed2868153be11f124 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -95,6 +95,7 @@ class Histogram::Factory {
           uint32_t bucket_count,
           int32_t flags)
     : Factory(name, HISTOGRAM, minimum, maximum, bucket_count, flags) {}
+  virtual ~Factory() = default;
 
   // Create histogram based on construction parameters. Caller takes
   // ownership of the returned object.
@@ -130,7 +131,7 @@ class Histogram::Factory {
   // Perform any required datafill on the just-created histogram.  If
   // overridden, be sure to call the "super" version -- this method may not
   // always remain empty.
-  virtual void FillHistogram(HistogramBase* histogram) {}
+  virtual void FillHistogram(HistogramBase* /* histogram */) {}
 
   // These values are protected (instead of private) because they need to
   // be accessible to methods of sub-classes in order to avoid passing
@@ -533,7 +534,7 @@ Histogram::Histogram(const std::string& name,
 Histogram::~Histogram() {
 }
 
-bool Histogram::PrintEmptyBucket(uint32_t index) const {
+bool Histogram::PrintEmptyBucket(uint32_t /* index */) const {
   return true;
 }
 
@@ -743,6 +744,7 @@ class LinearHistogram::Factory : public Histogram::Factory {
                          bucket_count, flags) {
     descriptions_ = descriptions;
   }
+  ~Factory() override = default;
 
  protected:
   BucketRanges* CreateRanges() override {
@@ -935,6 +937,7 @@ class BooleanHistogram::Factory : public Histogram::Factory {
  public:
   Factory(const std::string& name, int32_t flags)
     : Histogram::Factory(name, BOOLEAN_HISTOGRAM, 1, 2, 3, flags) {}
+  ~Factory() override = default;
 
  protected:
   BucketRanges* CreateRanges() override {
@@ -1023,6 +1026,7 @@ class CustomHistogram::Factory : public Histogram::Factory {
     : Histogram::Factory(name, CUSTOM_HISTOGRAM, 0, 0, 0, flags) {
     custom_ranges_ = custom_ranges;
   }
+  ~Factory() override = default;
 
  protected:
   BucketRanges* CreateRanges() override {
@@ -1136,7 +1140,8 @@ bool CustomHistogram::SerializeInfoImpl(Pickle* pickle) const {
   return true;
 }
 
-double CustomHistogram::GetBucketSize(Count current, uint32_t i) const {
+double CustomHistogram::GetBucketSize(Count /* current */,
+                                      uint32_t /* i */) const {
   return 1;
 }