Solution
Follow these easy steps to modify the URL for PHP debugging in Eclipse.
1. Create and save a debug configuration called "test". 2. Exit Eclipse. 3. Open workspace/.metadata/.plugins/org.eclipse.debug.core/.launches/test.launch with a text editor. 4. Change <stringattribute key="base_url" value="http://localhost/"/> to <stringattribute key="base_url" value="http://www.chtoen.com/"/> Replace http://www.chtoen.com/ with whatver URL you so desire. 5. Start Eclipse. 6. Go straight to debugging your PHP application with the "test" debug configuration. Do NOT navigate to "Debug Configuration..." because "Debug Configuration..." window will reset your URL.
The need to change base URL arises when you, for example, are trying to debug Facebook API, which only recognizes your actual website's domain, not localhost.
Questions? Let me know!