network_diagnostics: Add GetRandomAndFixedHostsWithScheme

Add GetRandomAndFixedHostsWithScheme() which will be used by network
diagnostics routines.

TEST=none
BUG=chromium:956783

Change-Id: Ia5073701ce97786e8ce5676a3db3444ef36b72c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2459513Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Kartik Hegde <khegde@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815282}

chrome/browser/chromeos/net/network_diagnostics/network_diagnostics_util.cc

@@ -90,6 +90,17 @@ std::vector<std::string> GetRandomHostsWithScheme(int num_hosts,
   return hosts;
 }
 
+std::vector<std::string> GetRandomAndFixedHostsWithScheme(int num_random_hosts,
+                                                          int prefix_length,
+                                                          std::string scheme) {
+  std::vector<std::string> hosts =
+      GetRandomHostsWithFixedHosts(num_random_hosts, prefix_length);
+  for (auto& host : hosts) {
+    host = scheme + host;
+  }
+  return hosts;
+}
+
 std::vector<std::string> GetRandomHostsWithSchemeAndGenerate204Path(
     int num_hosts,
     int prefix_length,

chrome/browser/chromeos/net/network_diagnostics/network_diagnostics_util.h

@@ -43,6 +43,12 @@ std::vector<std::string> GetRandomHostsWithScheme(int num_hosts,
                                                   int prefix_length,
                                                   std::string scheme);
 
+// Similar to GetRandomHostsWithFixedHosts, but with a |scheme| prepended to the
+// hosts.
+std::vector<std::string> GetRandomAndFixedHostsWithScheme(int num_random_hosts,
+                                                          int prefix_length,
+                                                          std::string scheme);
+
 // Similar to GetRandomHostsWithScheme, but with the 204 path appended to hosts.
 std::vector<std::string> GetRandomHostsWithSchemeAndGenerate204Path(
     int num_hosts,