Add blob scheme in Navigation Histograms

components/navigation_metrics/navigation_metrics.cc

 // Copyright 2013 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/navigation_metrics/navigation_metrics.h"
 
 #include "base/metrics/histogram.h"
 #include "url/gurl.h"
 
 namespace {
 
 enum Scheme {

[Ilya Sherman, 2015/06/09 19:53:36]

Please add documentation to indicate that this enum is used to back a histogram,
and should therefore be treated as append-only.

[Bhanu Dev, 2015/06/10 00:29:02]

Done.

   SCHEME_UNKNOWN,
   SCHEME_HTTP,
   SCHEME_HTTPS,
   SCHEME_FILE,
   SCHEME_FTP,
   SCHEME_DATA,
   SCHEME_JAVASCRIPT,
   SCHEME_ABOUT,
   SCHEME_CHROME,
+  SCHEME_BLOB,
   SCHEME_MAX,
 };
 
 const char* const kSchemeNames[] = {
   "unknown",
   url::kHttpScheme,
   url::kHttpsScheme,
   url::kFileScheme,
   url::kFtpScheme,
   url::kDataScheme,
   url::kJavaScriptScheme,
   url::kAboutScheme,
   "chrome",
+  url::kBlobScheme,
   "max",
 };
 
 static_assert(arraysize(kSchemeNames) == SCHEME_MAX + 1,
               "kSchemeNames should have SCHEME_MAX + 1 elements");
 
 }  // namespace
 
 namespace navigation_metrics {
 
 void RecordMainFrameNavigation(const GURL& url, bool is_in_page) {
   Scheme scheme = SCHEME_UNKNOWN;
   for (int i = 1; i < SCHEME_MAX; ++i) {
     if (url.SchemeIs(kSchemeNames[i])) {
       scheme = static_cast<Scheme>(i);
       break;
     }
   }
   UMA_HISTOGRAM_ENUMERATION("Navigation.MainFrameScheme", scheme, SCHEME_MAX);
   if (!is_in_page) {
     UMA_HISTOGRAM_ENUMERATION(
         "Navigation.MainFrameSchemeDifferentPage", scheme, SCHEME_MAX);
   }
 }
 
 }  // namespace navigation_metrics