You must make the android-support-v7-mediarouter project “aware” of the android-support-v7-appcompat project as a referenced library.
- Right click android-support-v7-mediarouter project, select Properties
- Select Android
- In the Library section at the bottom, click Add….
- Select android-support-v7-appcompat in the dialog.
- Click Apply.
- Click OK.
- Do a clean build on the android-support-v7-mediarouter project.