Remove histogram Net.Ntlm.HashDependsOnLocale

Enough data has been collected from the histogram
Net.Ntlm.HashDependsOnLocale and it is set to expire. Remove it.

BUG=1051924,1249094

Change-Id: I8d9a97acbc9d24e86f64ba7ccdcf8e2c9a374a5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3158984
Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Reviewed-by: Weilun Shi <sweilun@chromium.org>
Cr-Commit-Position: refs/heads/main@{#929077}

net/ntlm/ntlm.cc

@@ -8,9 +8,7 @@
 
 #include "base/check_op.h"
 #include "base/containers/span.h"
-#include "base/metrics/histogram_macros.h"
 #include "base/notreached.h"
-#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "net/base/net_string_util.h"
 #include "net/ntlm/ntlm_buffer_writer.h"
@@ -294,19 +292,15 @@ void GenerateNtlmHashV2(const std::u16string& domain,
                         base::span<uint8_t, kNtlmHashLen> v2_hash) {
   // NOTE: According to [MS-NLMP] Section 3.3.2 only the username and not the
   // domain is uppercased.
+
+  // TODO(https://crbug.com/1051924): Using a locale-sensitive upper casing
+  // algorithm is problematic. A more predictable approach would be to only
+  // uppercase ASCII characters, so the hash does not change depending on the
+  // user's locale.
   std::u16string upper_username;
   bool result = ToUpper(username, &upper_username);
   DCHECK(result);
 
-  // TODO(https://crbug.com/1051924): Using a locale-sensitive upper casing
-  // algorithm is problematic. A more predictable approach is to only uppercase
-  // ASCII characters, so the hash does not change depending on the user's
-  // locale. Histogram how often the locale-sensitive ToUpper() gives a result
-  // that differs from ASCII uppercasing, to see how often this ambiguity arises
-  // in practice.
-  UMA_HISTOGRAM_BOOLEAN("Net.Ntlm.HashDependsOnLocale",
-                        upper_username != base::ToUpperASCII(username));
-
   uint8_t v1_hash[kNtlmHashLen];
   GenerateNtlmHashV1(password, v1_hash);
   NtlmBufferWriter input_writer((upper_username.length() + domain.length()) *

tools/metrics/histograms/metadata/net/histograms.xml

@@ -2377,6 +2377,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Net.Ntlm.HashDependsOnLocale" enum="Boolean"
     expires_after="2021-10-25">
+  <obsolete>
+    Removed in 2021/09.
+  </obsolete>
   <owner>eroman@chromium.org</owner>
   <owner>src/net/OWNERS</owner>
   <summary>