Move g_metas_columns[] definition to .cc file

g_metas_columns was defined in a header file. This means that every
translation unit that uses the array gets its own copy - in Windows
official builds this means that chrome.dll got two copies. Not a huge
deal (the actual string constants were probably shared), but worth
fixing. This change moves the array definition to a .cc file.

The reason these duplicate arrays don't cause linker errors is because
they are static, both from explicitly being tagged as such and because
const globals are implicitly static.

Change-Id: Id25f2a7fd27a4ffa3e292437892468346c2dc053
Reviewed-on: https://chromium-review.googlesource.com/571214
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Stanislav Chiknavaryan <stanisc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486899}

components/sync/syncable/directory_backing_store.cc

@@ -39,6 +39,61 @@ using std::string;
 namespace syncer {
 namespace syncable {
 
+// Must be in exact same order as fields in entry_kernel.h.
+const ColumnSpec g_metas_columns[] = {
+    //////////////////////////////////////
+    // int64s
+    {"metahandle", "bigint primary key ON CONFLICT FAIL"},
+    {"base_version", "bigint default " CHANGES_VERSION_STRING},
+    {"server_version", "bigint default 0"},
+    // This is the item ID that we store for the embedding application.
+    {"local_external_id", "bigint default 0"},
+    {"transaction_version", "bigint default 0"},
+    // These timestamps are kept in the same format as that of the
+    // protocol (ms since Unix epoch).
+    {"mtime", "bigint default 0"},
+    {"server_mtime", "bigint default 0"},
+    {"ctime", "bigint default 0"},
+    {"server_ctime", "bigint default 0"},
+    //////////////////////////////////////
+    // Ids
+    {"id", "varchar(255) default \"r\""},
+    {"parent_id", "varchar(255) default \"r\""},
+    {"server_parent_id", "varchar(255) default \"r\""},
+    //////////////////////////////////////
+    // bits
+    {"is_unsynced", "bit default 0"},
+    {"is_unapplied_update", "bit default 0"},
+    {"is_del", "bit default 0"},
+    {"is_dir", "bit default 0"},
+    {"server_is_dir", "bit default 0"},
+    {"server_is_del", "bit default 0"},
+    //////////////////////////////////////
+    // Strings
+    {"non_unique_name", "varchar"},
+    {"server_non_unique_name", "varchar(255)"},
+    {"unique_server_tag", "varchar"},
+    {"unique_client_tag", "varchar"},
+    {"unique_bookmark_tag", "varchar"},
+    //////////////////////////////////////
+    // Blobs (serialized protos).
+    {"specifics", "blob"},
+    {"server_specifics", "blob"},
+    {"base_server_specifics", "blob"},
+    //////////////////////////////////////
+    // Blobs (positions).
+    {"server_unique_position", "blob"},
+    {"unique_position", "blob"},
+    //////////////////////////////////////
+    // AttachmentMetadata is a proto that contains all the metadata associated
+    // with an entry's attachments.  Each entry has only one AttachmentMetadata
+    // proto.  We store a single proto per entry (as opposed to one for each
+    // attachment) because it simplifies the database schema and implementation
+    // of
+    // DirectoryBackingStore.
+    {"attachment_metadata", "blob"},
+    {"server_attachment_metadata", "blob"}};
+
 // Increment this version whenever updating DB tables.
 const int32_t kCurrentDBVersion = 91;
 
@@ -205,6 +260,8 @@ void OnSqliteError(const base::Closure& catastrophic_error_handler,
 string ComposeCreateTableColumnSpecs() {
   const ColumnSpec* begin = g_metas_columns;
   const ColumnSpec* end = g_metas_columns + arraysize(g_metas_columns);
+  // Verify that the array was fully initialized.
+  DCHECK(g_metas_columns[arraysize(g_metas_columns) - 1].name != nullptr);
   string query;
   query.reserve(kUpdateStatementBufferSize);
   char separator = '(';

components/sync/syncable/entry_kernel.h

@@ -174,6 +174,7 @@ enum AttachmentMetadataField {
 enum {
   ATTACHMENT_METADATA_FIELDS_COUNT =
       ATTACHMENT_METADATA_FIELDS_END - ATTACHMENT_METADATA_FIELDS_BEGIN,
+  // If FIELD_COUNT is changed then g_metas_columns must be updated.
   FIELD_COUNT = ATTACHMENT_METADATA_FIELDS_END - BEGIN_FIELDS,
   // Past this point we have temporaries, stored in memory only.
   BEGIN_TEMPS = ATTACHMENT_METADATA_FIELDS_END,

components/sync/syncable/syncable_columns.h

@@ -17,67 +17,10 @@ struct ColumnSpec {
   const char* spec;
 };
 
-// Must be in exact same order as fields in entry_kernel.h.
-static const ColumnSpec g_metas_columns[] = {
-    //////////////////////////////////////
-    // int64s
-    {"metahandle", "bigint primary key ON CONFLICT FAIL"},
-    {"base_version", "bigint default " CHANGES_VERSION_STRING},
-    {"server_version", "bigint default 0"},
-    // This is the item ID that we store for the embedding application.
-    {"local_external_id", "bigint default 0"},
-    {"transaction_version", "bigint default 0"},
-    // These timestamps are kept in the same format as that of the
-    // protocol (ms since Unix epoch).
-    {"mtime", "bigint default 0"},
-    {"server_mtime", "bigint default 0"},
-    {"ctime", "bigint default 0"},
-    {"server_ctime", "bigint default 0"},
-    //////////////////////////////////////
-    // Ids
-    {"id", "varchar(255) default \"r\""},
-    {"parent_id", "varchar(255) default \"r\""},
-    {"server_parent_id", "varchar(255) default \"r\""},
-    //////////////////////////////////////
-    // bits
-    {"is_unsynced", "bit default 0"},
-    {"is_unapplied_update", "bit default 0"},
-    {"is_del", "bit default 0"},
-    {"is_dir", "bit default 0"},
-    {"server_is_dir", "bit default 0"},
-    {"server_is_del", "bit default 0"},
-    //////////////////////////////////////
-    // Strings
-    {"non_unique_name", "varchar"},
-    {"server_non_unique_name", "varchar(255)"},
-    {"unique_server_tag", "varchar"},
-    {"unique_client_tag", "varchar"},
-    {"unique_bookmark_tag", "varchar"},
-    //////////////////////////////////////
-    // Blobs (serialized protos).
-    {"specifics", "blob"},
-    {"server_specifics", "blob"},
-    {"base_server_specifics", "blob"},
-    //////////////////////////////////////
-    // Blobs (positions).
-    {"server_unique_position", "blob"},
-    {"unique_position", "blob"},
-    //////////////////////////////////////
-    // AttachmentMetadata is a proto that contains all the metadata associated
-    // with an entry's attachments.  Each entry has only one AttachmentMetadata
-    // proto.  We store a single proto per entry (as opposed to one for each
-    // attachment) because it simplifies the database schema and implementation
-    // of
-    // DirectoryBackingStore.
-    {"attachment_metadata", "blob"},
-    {"server_attachment_metadata", "blob"}};
-
-// At least enforce that there are equal number of column names and fields.
-static_assert(arraysize(g_metas_columns) >= FIELD_COUNT, "missing column name");
-static_assert(arraysize(g_metas_columns) <= FIELD_COUNT, "extra column names");
+extern const ColumnSpec g_metas_columns[FIELD_COUNT];
 
 static inline const char* ColumnName(int field) {
-  DCHECK(field < BEGIN_TEMPS);
+  DCHECK(field >= 0 && field < BEGIN_TEMPS);
   return g_metas_columns[field].name;
 }