Adding support for sampling crashes in Chrome on Windows.

chrome/install_static/install_util.h

 // Copyright 2016 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.
 // This file contains helper functions which provide information about the
 // current version of Chrome. This includes channel information, version
 // information etc. This functionality is provided by using functions in
 // kernel32 and advapi32. No other dependencies are allowed in this file.
 
 #ifndef CHROME_INSTALL_STATIC_INSTALL_UTIL_H_
 #define CHROME_INSTALL_STATIC_INSTALL_UTIL_H_
@@ skipping 23 matching lines @@
 extern const wchar_t kRegPathClientStateMedium[];
 extern const wchar_t kRegPathChromePolicy[];
 extern const wchar_t kRegApField[];
 extern const wchar_t kRegValueUsageStats[];
 extern const wchar_t kUninstallArgumentsField[];
 extern const wchar_t kMetricsReportingEnabled[];
 extern const wchar_t kAppGuidCanary[];
 extern const wchar_t kAppGuidGoogleChrome[];
 extern const wchar_t kAppGuidGoogleBinaries[];
 
+// Registry key to store the stats/crash sampling state of Chrome. If set to 1,
+// stats and crash reports will be uploaded in line with the user's consent,
+// otherwise, uploads will be dissabled. It is used to sample clients, to reduce

[robertshield, 2016/08/12 17:49:25]

s/dissabled/disabled/

[jwd, 2016/08/12 20:04:31]

Done.

+// server load for metics and crashes. This is controlled by the
+// MetricsReporting feature in chrome_metrics_services_manager_client.cc and is
+// written when metrics services are started up and when consent changes.
+extern const wchar_t kChromeStatsSampleKey[];

[Alexei Svitkine (slow), 2016/08/12 17:47:48]

Since this is no longer used outside of the .cc file, I would remove it from the
.h file and put it in an anon namespace in the .cc file with the comment.

[robertshield, 2016/08/12 17:49:25]

What is the relationship between the value stored here and the value stored at
kRegValueUsageStats which also seems to control UMA and crash reporting?

[jwd, 2016/08/12 20:04:30]

Done.

[jwd, 2016/08/12 20:04:31]

kRegValueUsageStats is the source of consent described in the above comment.
I've added a comment to that const.

+
 // TODO(ananta)
 // https://crbug.com/604923
 // Unify these constants with env_vars.h.
 extern const wchar_t kHeadless[];
 extern const wchar_t kShowRestart[];
 extern const wchar_t kRestartInfo[];
 extern const wchar_t kRtlLocale[];
 
 // TODO(ananta)
 // https://crbug.com/604923
@@ skipping 17 matching lines @@
 
 // Returns true if usage stats collecting is enabled for this user for the
 // current executable.
 bool GetCollectStatsConsent();
 
 // Returns true if usage stats collecting is enabled for this user for the
 // executable passed in as |exe_path|.
 // Only used by tests.
 bool GetCollectStatsConsentForTesting(const std::wstring& exe_path);
 
+// Returns true if the current executable is currently in the chosen sample that
+// will report stats and crashes.
+bool GetCollectStatsInSample();
+
+// Sets the registry value used for checking if Chrome is in the chosen sample
+// that will report stats and crashes. Returns true if writing was successful.
+bool SetCollectStatsInSample(bool in_sample);
+
 // Returns true if if usage stats reporting is controlled by a mandatory
 // policy. |metrics_is_enforced_by_policy| will be set to true accordingly.
 // TODO(ananta)
 // Make this function private to install_util.
 bool ReportingIsEnforcedByPolicy(bool* metrics_is_enforced_by_policy);
 
 // Initializes |g_process_type| which stores whether or not the current
 // process is the main browser process.
 void InitializeProcessType();
 
@@ skipping 116 matching lines @@
 // value of the |switch_name| passed in.
 std::string GetSwitchValueFromCommandLine(const std::string& command_line,
                                           const std::string& switch_name);
 
 // Caches the |ProcessType| of the current process.
 extern ProcessType g_process_type;
 
 }  // namespace install_static
 
 #endif  // CHROME_INSTALL_STATIC_INSTALL_UTIL_H_