Google Inc. unveiled payment services, security upgrades and access to HBO movies and shows for its popular Android software, seeking to push back against growing competition from rivals such as Apple Inc. The new version of the mobile software, called Android M, will include Android Pay, which lets users pay for merchandise at more than 700,000 stores in the U.S., Dave Burke, vice president of engineering for Android, said at the Internet company’s annual developers’ conference in San Francisco on Thursday.