DevTools: move front-end URL handling to DevToolsUIBindingds

BUG=662859

Review-Url: https://codereview.chromium.org/2607833002
Cr-Commit-Position: refs/heads/master@{#440926}
BrowserWindow* DevToolsWindow::GetInspectedBrowserWindow() {
  Browser* browser = NULL;
  int tab;
  return FindInspectedBrowserAndTabIndex(GetInspectedWebContents(),
                                         &browser, &tab) ?
      browser->window() : NULL;
}

BrowserWindow* DevToolsWindow::GetInspectedBrowserWindow() {
  Browser* browser = NULL;
  int tab;
  return FindInspectedBrowserAndTabIndex(GetInspectedWebContents(),
                                         &browser, &tab) ?
      browser->window() : NULL;
}
