Fix for non-sticky defaults bug. Added a bunch of tests.

chrome/browser/webdata/web_intents_table.cc

Index: chrome/browser/webdata/web_intents_table.cc
diff --git a/chrome/browser/webdata/web_intents_table.cc b/chrome/browser/webdata/web_intents_table.cc
index 90243112e2be6be5d6af888d6ce11148eecaa703..d68e29a8fdf0c4808eaf809cfac4fb82b745bc05 100644
--- a/chrome/browser/webdata/web_intents_table.cc
+++ b/chrome/browser/webdata/web_intents_table.cc
@@ -90,8 +90,16 @@ bool WebIntentsTable::Init() {
     if (!db_->Execute("CREATE INDEX IF NOT EXISTS web_intents_default_index"
                       " ON web_intents_defaults (scheme)"))
       return false;
+  } else {
+    // For a while, 'scheme' was set to null when setting a web_intents_defaults
+    // row. Due to a longstanding SQLite bug, a NULL entry in a unique key field
+    // is always considered distinct from any other NULL entry in that field,
+    // rendering the uniqueness obsolete. Get rid of any such entries.
+    if (!db_->Execute("DELETE FROM web_intents_defaults WHERE scheme IS NULL"))

[Steve McKay, 2012/09/14 18:57:00]

This'll ding startup time. We can do this one and only once in a database
version upgrade.

Feel free to do this in a different CL + add a tracking bug. Might be a good bug
for rouslan to get to know the database update system.

[Greg Billock, 2012/09/14 19:12:28]

Scott, should we roll DB versions for this?

[Scott Hess - ex-Googler, 2012/09/14 19:37:47]

The UNIQUE constraint will be enforced by a tree keyed by the items in order. 
Since scheme is the second item in, this delete would effectively be a full
table scan, so it could be expensive to do every time.  [Depending on table
size, and what else you'll be getting up to with the table, etc.]

If you do version things, I suggest you add NOT NULL constraints to the columns
you want these to apply to.  That'll involve creating a new table and shuffling
things over, as the migration below already does.  Of course, that potentially
means you'll discover other cases where those columns are NULL, so you'll want
IS NOT NULL clauses in the WHERE of the INSERT-SELECT.

+      return false;
   }
 
+
   return true;
 }
 
@@ -300,14 +308,16 @@ bool WebIntentsTable::SetDefaultService(
     const DefaultWebIntentService& default_service) {
   sql::Statement s(db_->GetUniqueStatement(
       "INSERT OR REPLACE INTO web_intents_defaults "
-      "(action, type, url_pattern, user_date, suppression, service_url) "
-      "VALUES (?, ?, ?, ?, ?, ?)"));
+      "(action, type, url_pattern, user_date, suppression,"
+      " service_url, scheme) "
+      "VALUES (?, ?, ?, ?, ?, ?, ?)"));
   s.BindString16(0, default_service.action);
   s.BindString16(1, default_service.type);
   s.BindString(2, default_service.url_pattern.GetAsString());
   s.BindInt(3, default_service.user_date);
   s.BindInt64(4, default_service.suppression);
   s.BindString(5, default_service.service_url);
+  s.BindString16(6, default_service.scheme);
 
   return s.Run();
 }