Change logging of about:flags from actions to a histogram.

chrome/browser/about_flags.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_ABOUT_FLAGS_H_
 #define CHROME_BROWSER_ABOUT_FLAGS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 69 matching lines @@
 // Reset all flags to the default state by clearing all flags.
 void ResetAllFlags(flags_ui::FlagsStorage* flags_storage);
 
 // Sends UMA stats about experimental flag usage. This should be called once per
 // startup.
 void RecordUMAStatistics(flags_ui::FlagsStorage* flags_storage);
 
 // Returns the UMA id for the specified switch name.
 base::HistogramBase::Sample GetSwitchUMAId(const std::string& switch_name);
 
-// Sends stats (as UMA histogram) about command_line_difference.
-// This is used on ChromeOS to report flags that lead to browser restart.
-// |command_line_difference| is the result of
-// AreSwitchesIdenticalToCurrentCommandLine().
-void ReportCustomFlags(const std::string& uma_histogram_hame,
-                       const std::set<std::string>& command_line_difference);
+// Sends stats (as UMA histogram) about a set of command line |flags| in
+// a histogram, with an enum value for each flag in |flags|, based on the
+// hash of the flag name.
+void ReportAboutFlagsHistogram(const std::string& uma_histogram_hame,

[Ilya Sherman, 2016/08/29 22:31:29]

nit: s/hame/name here too :)

[Alexei Svitkine (slow), 2016/08/30 15:04:22]

Done.

+                               const std::set<std::string>& flags);
 
 namespace testing {
 
 // Returns the global set of feature entries.
 const flags_ui::FeatureEntry* GetFeatureEntries(size_t* count);
 
 // This value is reported as switch histogram ID if switch name has unknown
 // format.
 extern const base::HistogramBase::Sample kBadSwitchFormatHistogramId;
 
 }  // namespace testing
 
 }  // namespace about_flags
 
 #endif  // CHROME_BROWSER_ABOUT_FLAGS_H_