Clean up dns prefetch code, and also port it.

- remove slave threads and use HostResolver in asynchronous mode instead (while still limiting number of concurrent lookups)

- make the implementation portable and make DnsMaster unit test compile and pass on Linux

- add more tests to DnsMaster unit test to simulate various shutdown scenarios, concurrent lookups, and to verify that we don't exceed our limit of concurrent lookup requests)

- remove some tests which relied on specifics of slaves' inner working

- adjust initialization and shutdown of dns prefetching (now it relies on the IO message loop being present)

Bonus: shutdown is almost instant now, no need to have a timeout.

BUG=5687, 6683

Review URL: http://codereview.chromium.org/15076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10021 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 2 insertions, 4 deletions

diff --git a/chrome/browser/net/dns_host_info_unittest.cc b/chrome/browser/net/dns_host_info_unittest.cc
index c279804..a079716 100644
--- a/chrome/browser/net/dns_host_info_unittest.cc
+++ b/chrome/browser/net/dns_host_info_unittest.cc
@@ -41,8 +41,7 @@ TEST(DnsHostInfoTest, StateChangeTest) {
   EXPECT_FALSE(info.NeedsDnsUpdate(hostname1))
     << "update needed after being queued";
   info.SetAssignedState();
-  EXPECT_FALSE(info.NeedsDnsUpdate(hostname1))
-    << "update needed while assigned to slave";
+  EXPECT_FALSE(info.NeedsDnsUpdate(hostname1));
   info.SetFoundState();
   EXPECT_FALSE(info.NeedsDnsUpdate(hostname1))
     << "default expiration time is TOOOOO short";
@@ -64,8 +63,7 @@ TEST(DnsHostInfoTest, StateChangeTest) {
   // be found.  We'll sleep for a while, and then come back with not-found.
   info.SetQueuedState(DnsHostInfo::UNIT_TEST_MOTIVATED);
   info.SetAssignedState();
-  EXPECT_FALSE(info.NeedsDnsUpdate(hostname1))
-    << "update needed while assigned to slave";
+  EXPECT_FALSE(info.NeedsDnsUpdate(hostname1));
   // Greater than minimal expected network latency on DNS lookup.
   PlatformThread::Sleep(25);
   info.SetNoSuchNameState();