Clean up dns prefetch code, and also port it.

BUG=5687, 6683

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

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8625 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 26 insertions, 8 deletions

diff --git a/net/base/host_resolver.h b/net/base/host_resolver.h
index 1f649f8..fa07708 100644
--- a/net/base/host_resolver.h
+++ b/net/base/host_resolver.h
@@ -41,10 +41,9 @@ class HostResolver {
   //
   // When callback is null, the operation completes synchronously.
   //
-  // When callback is non-null, ERR_IO_PENDING is returned if the operation
-  // could not be completed synchronously, in which case the result code will
-  // be passed to the callback when available.
-  //
+  // When callback is non-null, the operation will be performed asynchronously.
+  // ERR_IO_PENDING is returned if it has been scheduled successfully. Real
+  // result code will be passed to the completion callback.
   int Resolve(const std::string& hostname, int port,
               AddressList* addresses, CompletionCallback* callback);
 
@@ -74,7 +73,7 @@ class HostMapper {
 // function while there are no outstanding HostResolver instances.
 //
 // NOTE: In most cases, you should use ScopedHostMapper instead, which is
-// defined in host_resolver_unittest.h
+// defined in scoped_host_resolver.h.
 //
 HostMapper* SetHostMapper(HostMapper* host_mapper);
 #endif
diff --git a/net/base/scoped_host_mapper.h b/net/base/scoped_host_mapper.h
index 836cb34..8b623b9 100644
--- a/net/base/scoped_host_mapper.h
+++ b/net/base/scoped_host_mapper.h
@@ -39,6 +39,7 @@
 #include <list>
 
 #include "base/string_util.h"
+#include "base/platform_thread.h"
 #include "net/base/host_resolver.h"
 #include "net/base/net_errors.h"
 
@@ -63,12 +64,22 @@ class ScopedHostMapper : public HostMapper {
     rules_.push_back(Rule(host_pattern, replacement));
   }
 
+  void AddRuleWithLatency(const char* host_pattern, const char* replacement,
+                          int latency) {
+    rules_.push_back(Rule(host_pattern, replacement, latency));
+  }
+
  private:
   std::string Map(const std::string& host) {
-    RuleList::const_iterator r;
+    RuleList::iterator r;
     for (r = rules_.begin(); r != rules_.end(); ++r) {
-      if (MatchPattern(host, r->host_pattern))
+      if (MatchPattern(host, r->host_pattern)) {
+        if (r->latency != 0) {
+          PlatformThread::Sleep(r->latency);
+          r->latency = 1;  // Simulate cache warmup.
+        }
         return r->replacement;
+      }
     }
     return previous_host_mapper_ ? previous_host_mapper_->Map(host) : host;
   }
@@ -76,7 +87,15 @@ class ScopedHostMapper : public HostMapper {
   struct Rule {
     std::string host_pattern;
     std::string replacement;
-    Rule(const char* h, const char* r) : host_pattern(h), replacement(r) {}
+    int latency;  // in milliseconds
+    Rule(const char* h, const char* r)
+        : host_pattern(h),
+          replacement(r),
+          latency(0) {}
+    Rule(const char* h, const char* r, const int l)
+        : host_pattern(h),
+          replacement(r),
+          latency(l) {}
   };
   typedef std::list<Rule> RuleList;