Support speculative pre-connection to search URLs

Implement several flavors of TCP/IP speculative preconnection
under a command line flag (not yet on by default).

The first area of preconnection takes place when a user types
a query into the omnibox, as we preconnect to the search service
when the omnibox suggests it is going to do a search.

The second area involves subresources, such as images.
When a navigation takes place, and we've seen navigations
to that domain/port before, and the history-based 
probabability that we'll need to make a connection to
a second site (host/port) is sufficiently large, then we
preconnect to that second site while we are still connecting
to the primary site (and before we've gotten content from
the primary site.

We also fall-back to mere DNS pre-resolution of subresource
hostnames when the probability of a connection to the
subresource is not high enough.

BUG=42694
r=pkasting,willchan,mbelshe
Review URL: http://codereview.chromium.org/1585029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47479 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 0 deletions

diff --git a/net/base/host_port_pair.h b/net/base/host_port_pair.h
index 35d244e..78f74ea 100644
--- a/net/base/host_port_pair.h
+++ b/net/base/host_port_pair.h
@@ -17,12 +17,18 @@ struct HostPortPair {
 
   // TODO(willchan): Define a functor instead.
   // Comparator function so this can be placed in a std::map.
+  // TODO(jar): Violation of style guide, and should be removed.
   bool operator<(const HostPortPair& other) const {
     if (port != other.port)
       return port < other.port;
     return host < other.host;
   }
 
+  // Equality test of contents. (Probably another violation of style guide).
+  bool Equals(const HostPortPair& other) const {
+    return host == other.host && port == other.port;
+  }
+
   // ToString() will convert the HostPortPair to "host:port".  If |host| is an
   // IPv6 literal, it will add brackets around |host|.
   std::string ToString() const;