Add private methods for chromedriver binary executable

lib/Selenium/Chrome.pm

@@ -15,6 +15,35 @@ has '+browser_name' => (
     default => sub { 'chrome' }
 );
 
+sub _find_executable {
+    my ($binary) = @_;
+
+    my $executable = which($binary);
+
+    if (not defined $executable) {
+        warn q(
+Unable to find the chromedriver binary in your $PATH. Please download the server from http://chromedriver.storage.googleapis.com/index.html and place it somewhere on your $PATH. More info is available at http://code.google.com/p/selenium/wiki/ChromeDriver.
+
+We'll try falling back to standard Remote Driver mode via the webdriver.chrome.driver property...
+);
+    }
+
+    return $executable;
+}
+
+sub _construct_command {
+    my ($executable, $port) = @_;
+
+    my %args = (
+        'base-url' => 'wd/hub',
+        'port' => $port
+    );
+
+    my @args = map { '--' . $_ . '=' . $args{$_} } keys %args;
+
+    return join(' ', ($executable, @args, '> /dev/null 2>&1 &') );
+}
+
 sub _find_open_port_above {
     my ($port) = @_;