Add metrics for tracking LoginDatabase::Init failure.

components/password_manager/core/browser/login_database.cc

Index: components/password_manager/core/browser/login_database.cc
diff --git a/components/password_manager/core/browser/login_database.cc b/components/password_manager/core/browser/login_database.cc
index aed24009203c7047b2f94d5c500efe68c4e3d4e5..0719a61e314c32a7e92ef182aeb87b2582ae69cc 100644
--- a/components/password_manager/core/browser/login_database.cc
+++ b/components/password_manager/core/browser/login_database.cc
@@ -84,6 +84,19 @@ enum LoginTableColumns {
 
 enum class HistogramSize { SMALL, LARGE };
 
+enum DatabaseInitError {

[Ilya Sherman, 2015/08/13 00:34:18]

Please document that this is used to back an UMA histogram, and therefore should
be treated as append-only.

[vasilii, 2015/08/13 09:04:33]

Done.

+  OPEN_FILE_ERROR,
+  START_TRANSACTION_ERROR,
+  META_TABLE_INIT_ERROR,
+  INCOMPATIBLE_VERSION,
+  INIT_LOGINS_ERROR,
+  INIT_STATS_ERROR,
+  MIGRATION_ERROR,
+  COMMIT_TRANSACTION_ERROR,
+
+  DATABASE_INIT_ERROR_COUNT,
+};
+
 void BindAddStatement(const PasswordForm& form,
                       const std::string& encrypted_password,
                       sql::Statement* s) {
@@ -297,12 +310,17 @@ bool LoginDatabase::Init() {
   db_.set_histogram_tag("Passwords");
 
   if (!db_.Open(db_path_)) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              OPEN_FILE_ERROR, DATABASE_INIT_ERROR_COUNT);

[Ilya Sherman, 2015/08/13 00:34:18]

Please create a wrapper function for emitting to this histogram, so that you can
call it as "LogDatabaseInitError(OPEN_FILE_ERROR);".

[vasilii, 2015/08/13 09:04:33]

Done.

     LOG(ERROR) << "Unable to open the password store database.";
     return false;
   }
 
   sql::Transaction transaction(&db_);
   if (!transaction.Begin()) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              START_TRANSACTION_ERROR,
+                              DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Unable to start a transaction.";
     db_.Close();
     return false;
@@ -311,11 +329,15 @@ bool LoginDatabase::Init() {
   // Check the database version.
   if (!meta_table_.Init(&db_, kCurrentVersionNumber,
                         kCompatibleVersionNumber)) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              META_TABLE_INIT_ERROR, DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Unable to create the meta table.";
     db_.Close();
     return false;
   }
   if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              INCOMPATIBLE_VERSION, DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Password store database is too new, kCurrentVersionNumber="
                << kCurrentVersionNumber << ", GetCompatibleVersionNumber="
                << meta_table_.GetCompatibleVersionNumber();
@@ -325,12 +347,16 @@ bool LoginDatabase::Init() {
 
   // Initialize the tables.
   if (!InitLoginsTable()) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              INIT_LOGINS_ERROR, DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Unable to initialize the logins table.";
     db_.Close();
     return false;
   }
 
   if (!stats_table_.Init(&db_)) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              INIT_STATS_ERROR, DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Unable to initialize the stats table.";
     db_.Close();
     return false;
@@ -338,6 +364,10 @@ bool LoginDatabase::Init() {
 
   // If the file on disk is an older database version, bring it up to date.
   if (!MigrateOldVersionsAsNeeded()) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              MIGRATION_ERROR, DATABASE_INIT_ERROR_COUNT);
+    UMA_HISTOGRAM_CUSTOM_COUNTS("PasswordManager.LoginDatabaseFailedVersion",
+                                meta_table_.GetVersionNumber(), 1, 30, 30);

[Ilya Sherman, 2015/08/13 00:34:18]

nit: Would a sparse histogram be appropriate here?

[vasilii, 2015/08/13 09:04:33]

Done.

     LOG(ERROR) << "Unable to migrate database from "
                << meta_table_.GetVersionNumber() << " to "
                << kCurrentVersionNumber;
@@ -346,6 +376,9 @@ bool LoginDatabase::Init() {
   }
 
   if (!transaction.Commit()) {
+    UMA_HISTOGRAM_ENUMERATION("PasswordManager.LoginDatabaseInit",
+                              COMMIT_TRANSACTION_ERROR,
+                              DATABASE_INIT_ERROR_COUNT);
     LOG(ERROR) << "Unable to commit a transaction.";
     db_.Close();
     return false;