Cookie store: Remove iOS special casing in the schema.

The current schema creates a full index for iOS, and a partial index on
all other platforms. This was done because the SQLite versions that
shipped in iOS 8.1 and before did not have partial index support.

This CL removes the special-casing for iOS. Chrome now requires iOS 10+,
which ships with a sufficiently modern of SQLite. The difference should
not be visible outside small variations in space usage and query
processing times, so it's safe to let the old schema instances die off
as the iOS fleet is organically refreshed.

Change-Id: Iac461c83cc121fbdc98dd12c91ff5eef57eec4ed
Reviewed-on: https://chromium-review.googlesource.com/889921Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Randy Smith <rdsmith@chromium.org>
Commit-Queue: Randy Smith <rdsmith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532928}

net/extras/sqlite/sqlite_persistent_cookie_store.cc

@@ -457,15 +457,9 @@ bool InitTable(sql::Connection* db) {
   if (!db->Execute("CREATE INDEX domain ON cookies(host_key)"))
     return false;
 
-#if defined(OS_IOS)
-  // iOS 8.1 and older doesn't support partial indices. iOS 8.2 supports
-  // partial indices.
-  if (!db->Execute("CREATE INDEX is_transient ON cookies(persistent)")) {
-#else
   if (!db->Execute(
           "CREATE INDEX is_transient ON cookies(persistent) "
           "where persistent != 1")) {
-#endif
     return false;
   }