Workaround to remove command line flag on ChromeOS.

When bookmarks experiment is enabled existing code will add a command line flag that will allow opt-out to be shown on a chrome:flags page.
On Chrome OS at time of login if they see command line flag from any experiment they restart browser. It creates delay and user will see a black screen for a couple seconds. It happens on every login, not only the first one.
I talked to CrOS devs and they strongly discourage from using command line flags.
So for Chrome OS only do not add flag to command line but still keep it in a flag_storage. Use flag storage when need to check if flag is set.

BUG=

Review URL: https://codereview.chromium.org/578333003

Cr-Commit-Position: refs/heads/master@{#296504}

chrome/browser/about_flags.cc

@@ -2023,7 +2023,8 @@ void GetSanitizedEnabledFlags(
   *result = flags_storage->GetFlags();
 }
 
-bool SkipConditionalExperiment(const Experiment& experiment) {
+bool SkipConditionalExperiment(const Experiment& experiment,
+                               FlagsStorage* flags_storage) {
   if (experiment.internal_name ==
       std::string("enhanced-bookmarks-experiment")) {
 #if defined(OS_ANDROID)
@@ -2036,7 +2037,7 @@ bool SkipConditionalExperiment(const Experiment& experiment) {
     if (command_line->HasSwitch(switches::kEnhancedBookmarksExperiment))
       return false;
 
-    return !IsEnhancedBookmarksExperimentEnabled();
+    return !IsEnhancedBookmarksExperimentEnabled(flags_storage);
 #endif
   }
 
@@ -2178,7 +2179,7 @@ void GetFlagsExperimentsData(FlagsStorage* flags_storage,
 
   for (size_t i = 0; i < num_experiments; ++i) {
     const Experiment& experiment = experiments[i];
-    if (SkipConditionalExperiment(experiment))
+    if (SkipConditionalExperiment(experiment, flags_storage))
       continue;
 
     base::DictionaryValue* data = new base::DictionaryValue();
@@ -2375,6 +2376,14 @@ void FlagsState::ConvertFlagsToSwitches(FlagsStorage* flags_storage,
       continue;
     }
 
+#if defined(OS_CHROMEOS)
+    // On Chrome OS setting command line flag may make browser to restart on
+    // user login. As this flag eventually will be set to a significant number
+    // of users skip manual-enhanced-bookmarks to avoid restart.
+    if (experiment_name == "manual-enhanced-bookmarks")
+      continue;
+#endif
+
     const std::pair<std::string, std::string>&
         switch_and_value_pair = name_to_switch_it->second;
 

chrome/browser/bookmarks/DEPS

@@ -34,4 +34,10 @@ specific_include_rules = {
     "+chrome/test/base/testing_profile.h",
     "+chrome/utility/importer/bookmark_html_reader.h",
   ],
+  # Allow to include flags_storage into enhanced_bookmarks_features.cc because
+  # it has a function used by about_flags.cc and it needs flags_storage.
+  # This should be removed after enhanced bookmarks experiment is over.
+  'enhanced_bookmarks_features\.cc': [
+    "+chrome/browser/flags_storage.h",
+  ],
 }

chrome/browser/bookmarks/enhanced_bookmarks_features.cc

@@ -11,6 +11,7 @@
 #include "base/sha1.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/flags_storage.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/common/chrome_switches.h"
@@ -190,12 +191,23 @@ void ForceFinchBookmarkExperimentIfNeeded(
   }
 }
 
-bool IsEnhancedBookmarksExperimentEnabled() {
+bool IsEnhancedBookmarksExperimentEnabled(
+    about_flags::FlagsStorage* flags_storage) {
+#if defined(OS_CHROMEOS)
+  // We are not setting command line flags on Chrome OS to avoid browser restart
+  // but still have flags in flags_storage. So check flags_storage instead.
+  const std::set<std::string> flags = flags_storage->GetFlags();
+  if (flags.find(switches::kManualEnhancedBookmarks) != flags.end())
+    return true;
+  if (flags.find(switches::kManualEnhancedBookmarksOptout) != flags.end())
+    return true;
+#else
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kManualEnhancedBookmarks) ||
       command_line->HasSwitch(switches::kManualEnhancedBookmarksOptout)) {
     return true;
   }
+#endif
 
   return IsEnhancedBookmarksExperimentEnabledFromFinch();
 }

chrome/browser/bookmarks/enhanced_bookmarks_features.h

@@ -9,6 +9,10 @@
 
 #include "extensions/common/extension.h"
 
+namespace about_flags {
+class FlagsStorage;
+}  // namespace about_flags
+
 class PrefService;
 class Profile;
 
@@ -54,7 +58,8 @@ void ForceFinchBookmarkExperimentIfNeeded(
 // Experiment could run by Chrome sync or by Finch.
 // Note that this doesn't necessarily mean that enhanced bookmarks
 // is enabled, e.g., user can opt out using a flag.
-bool IsEnhancedBookmarksExperimentEnabled();
+bool IsEnhancedBookmarksExperimentEnabled(
+    about_flags::FlagsStorage* flags_storage);
 
 #if defined(OS_ANDROID)
 // Returns true if enhanced bookmark salient image prefetching is enabled.