De acordo com este , esse erro é esperado. Eles não assinam o plug-in do Android.
Eu quero instalar o plug-in do Eclipse, mas não funciona. e esse é o detalhe.
Warning: You are installing software that contains unsigned content. The authenticity or validity of this software cannot be established. Do you want to continue with the installation?
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.adt_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.adt_20.0.3.v201208082019-427395
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.base_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.ddms_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.ddms_20.0.3.v201208082019-427395
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.gldebugger_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.gldebugger_20.0.3.v201208082019-427395
/home/geekerstyle/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.hierarchyviewer_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.hierarchyviewer_20.0.3.v201208082019-427395
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.ndk_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.ndk_20.0.3.v201208082019-427395
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/com.android.ide.eclipse.traceview_20.0.3.v201208082019-427395.jar
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/features/com.android.ide.eclipse.traceview_20.0.3.v201208082019-427395
/home/adm/.eclipse/org.eclipse.platform_4.2.0_1473617060/plugins/overlay.com.android.ide.eclipse.adt.overlay_20.0.3.v201208082019-427395.jar
De acordo com este , esse erro é esperado. Eles não assinam o plug-in do Android.