Add a flag for the password manager force-saving experiment.

There is no functionality behind this flag yet.

I kept the name "force-saving", since this name of the feature is quite established now, although I wonder whether saying "manually save" wouldn't be more understandable in the description.

BUG=484891

Review URL: https://codereview.chromium.org/1140043003

Cr-Commit-Position: refs/heads/master@{#330438}

chrome/app/generated_resources.grd

@@ -6373,6 +6373,12 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_PASSWORD_MANAGER_REAUTHENTICATION_DESCRIPTION" desc="Description of the flag for the password manager reauthentication option.">
         Disable prompting the user for their OS password before revealing passwords on the passwords page.
       </message>
+      <message name="IDS_FLAGS_ENABLE_PASSWORD_FORCE_SAVING_NAME" desc="Name of the flag for the password manager's force-saving option.">
+        Enable force-saving of passwords
+      </message>
+      <message name="IDS_FLAGS_ENABLE_PASSWORD_FORCE_SAVING_DESCRIPTION" desc="Description of the flag for the password manager's force-saving option.">
+        Allow the user to manually enforce password saving instead of relying on password manager's heuristics.
+      </message>      
       <message name="IDS_FLAGS_PASSWORD_MANAGER_LINK_NAME" desc="Name of the flag to enable showing a link to account central on password settings page">
         Enable remote password management link
       </message>

chrome/browser/about_flags.cc

@@ -1152,6 +1152,14 @@ const Experiment kExperiments[] = {
     kOsMac | kOsWin,
     SINGLE_VALUE_TYPE(switches::kDisablePasswordManagerReauthentication)
   },
+  {
+    "enable-password-force-saving",
+    IDS_FLAGS_ENABLE_PASSWORD_FORCE_SAVING_NAME,
+    IDS_FLAGS_ENABLE_PASSWORD_FORCE_SAVING_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(
+        password_manager::switches::kEnablePasswordForceSaving)
+  },
   {
     "enable-password-link",
     IDS_FLAGS_PASSWORD_MANAGER_LINK_NAME,

components/password_manager/core/common/experiments.cc

@@ -24,4 +24,9 @@ bool ManageAccountLinkExperimentEnabled() {
   return group_name == "Enabled";
 }
 
+bool ForceSavingExperimentEnabled() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      password_manager::switches::kEnablePasswordForceSaving);
+}
+
 }  // namespace password_manager

components/password_manager/core/common/experiments.h

@@ -11,6 +11,9 @@ namespace password_manager {
 // settings.
 bool ManageAccountLinkExperimentEnabled();
 
+// True iff the force-saving of passwords is enabled.
+bool ForceSavingExperimentEnabled();
+
 }  // namespace password_manager
 
 #endif  // COMPONENTS_PASSWORD_MANAGER_CORE_COMMON_EXPERIMENTS_H_

components/password_manager/core/common/password_manager_switches.cc

@@ -58,6 +58,10 @@ const char kEnableManagerForSyncSignin[] = "enable-manager-for-sync-signin";
 // central.
 const char kEnablePasswordLink[] = "enable-password-link";
 
+// Enable a context menu item in the password field that allows the user
+// to manually enforce saving of their password.
+const char kEnablePasswordForceSaving[] = "enable-password-force-saving";
+
 }  // namespace switches
 
 }  // namespace password_manager

components/password_manager/core/common/password_manager_switches.h

@@ -24,6 +24,7 @@ extern const char kEnableAutomaticPasswordSaving[];
 extern const char kEnableDropSyncCredential[];
 extern const char kEnableManagerForSyncSignin[];
 extern const char kEnablePasswordLink[];
+extern const char kEnablePasswordForceSaving[];
 
 }  // namespace switches
 

tools/metrics/histograms/histograms.xml

@@ -56750,6 +56750,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="-1102212525" label="enable-tcp-fastopen"/>
   <int value="-1078093206" label="ash-debug-shortcuts"/>
   <int value="-1077752943" label="enable-password-generation"/>
+  <int value="-1062119671" label="enable-password-force-saving"/>
   <int value="-1056310158" label="disable-memory-pressure-chromeos"/>
   <int value="-1052782474" label="enable-cloud-devices"/>
   <int value="-1052415111" label="malware-interstitial-v2"/>