Refactor of Histogram related code

base/metrics/bucket_ranges_unittest.cc

Index: base/metrics/bucket_ranges_unittest.cc
===================================================================
--- base/metrics/bucket_ranges_unittest.cc	(revision 148055)
+++ base/metrics/bucket_ranges_unittest.cc	(working copy)
@@ -71,5 +71,21 @@
   EXPECT_TRUE(ranges.HasValidChecksum());
 }
 
+// Table was generated similarly to sample code for CRC-32 given on:
+// http://www.w3.org/TR/PNG/#D-CRCAppendix.
+TEST(HistogramTest, Crc32TableTest) {
+  for (int i = 0; i < 256; ++i) {
+    uint32 checksum = i;
+    for (int j = 0; j < 8; ++j) {
+      const uint32 kReversedPolynomial = 0xedb88320L;
+      if (checksum & 1)
+        checksum = kReversedPolynomial ^ (checksum >> 1);
+      else
+        checksum >>= 1;
+    }
+    EXPECT_EQ(kCrcTable[i], checksum);
+  }
+}
+
 }  // namespace
 }  // namespace base