Added API for checking if BASE_URI

The contribution provides an API to check if the location is the
location where custom texts are loaded in a browser. By construct,
"about:blank" is used for that purpose. This API can be adapted by the
clients instead of explicitly defining the string and checking.

Contributes to #213

bundles/org.eclipse.swt/Eclipse SWT Browser/common/org/eclipse/swt/browser/Browser.java

@@ -13,6 +13,8 @@
  *******************************************************************************/
 package org.eclipse.swt.browser;
 
+import java.net.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.widgets.*;
 
@@ -52,6 +54,7 @@ public class Browser extends Composite {
 	static final String NO_INPUT_METHOD = "org.eclipse.swt.internal.gtk.noInputMethod"; //$NON-NLS-1$
 	static final String PACKAGE_PREFIX = "org.eclipse.swt.browser."; //$NON-NLS-1$
 	static final String PROPERTY_DEFAULTTYPE = "org.eclipse.swt.browser.DefaultType"; //$NON-NLS-1$
+	private static final URI BASE_URI = URI.create("about:blank");
 
 /**
  * Constructs a new instance of this class given its parent
@@ -1201,4 +1204,16 @@ public void stop () {
 	checkWidget();
 	webBrowser.stop ();
 }
+
+/**
+ * Checks if the location supplied is the location for setting custom text in the browser
+ *
+ * @param location the URL to be checked
+ *
+ * @since 3.127
+ */
+public static boolean isLocationForCustomText(String location) {
+	return URI.create(location).equals(Browser.BASE_URI)
+			|| location.startsWith("data:");
+}
 }