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, 4 insertions, 1 deletions

diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index caaa963..c68d4a6 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -30,6 +30,7 @@
 #include "chrome/browser/dom_ui/chrome_url_data_manager.h"
 #include "chrome/browser/first_run.h"
 #include "chrome/browser/metrics/metrics_service.h"
+#include "chrome/browser/net/dns_global.h"
 #include "chrome/browser/profile_manager.h"
 #include "chrome/browser/shell_integration.h"
 #include "chrome/common/chrome_constants.h"
@@ -108,7 +109,7 @@ void WillTerminate();
 
 #if defined(OS_WIN) || defined(OS_LINUX)
 // Perform any platform-specific work that needs to be done before the main
-// message loop is created and initialized. 
+// message loop is created and initialized.
 void WillInitializeMainMessageLoop(const CommandLine & command_line) {
 }
 
@@ -442,12 +443,14 @@ int BrowserMain(const MainFunctionParams& parameters) {
 #if defined(OS_WIN)
   // Initialize Winsock.
   net::EnsureWinsockInit();
+#endif  // defined(OS_WIN)
 
   // Initialize the DNS prefetch system
   chrome_browser_net::DnsPrefetcherInit dns_prefetch_init(user_prefs);
   chrome_browser_net::DnsPrefetchHostNamesAtStartup(user_prefs, local_state);
   chrome_browser_net::RestoreSubresourceReferrers(local_state);
 
+#if defined(OS_WIN)
   // Init common control sex.
   INITCOMMONCONTROLSEX config;
   config.dwSize = sizeof(config);