DevTools: move front-end URL handling to DevToolsUIBindingds

BUG=662859

Review-Url: https://codereview.chromium.org/2607833002
Cr-Commit-Position: refs/heads/master@{#440926}
void DevToolsUIBindings::SetWhitelistedShortcuts(const std::string& message) {
  delegate_->SetWhitelistedShortcuts(message);
}

void DevToolsUIBindings::SetWhitelistedShortcuts(const std::string& message) {
  delegate_->SetWhitelistedShortcuts(message);
}
