allow passing doclava options for grouping

This allows creating online docs for sub-groups.

Bug: 37484958
Test: gw generateDocs
Change-Id: I12b3965ce560a04d5246ba6e67287c287ce35422
diff --git a/buildSrc/diff_and_docs.gradle b/buildSrc/diff_and_docs.gradle
index 6bace56..47fcefc 100644
--- a/buildSrc/diff_and_docs.gradle
+++ b/buildSrc/diff_and_docs.gradle
@@ -70,7 +70,7 @@
 
 // Generates online docs.
 task generateDocs(type: DoclavaTask, dependsOn: [configurations.doclava, generateSdkApi]) {
-    def offlineDocs = project.buildOfflineDocs
+    def offlineDocs = project.docs.offline
     group = JavaBasePlugin.DOCUMENTATION_GROUP
     description = 'Generates d.android.com-style documentation. To generate offline docs use ' +
             '\'-PofflineDocs=true\' parameter.'
@@ -124,7 +124,8 @@
         if (!offlineDocs) {
             addStringOption "toroot", "/"
             addBooleanOption "devsite", true
-            addBooleanOption "androidSupportRef", true
+            addStringOption "dac_libraryroot", project.docs.dac.libraryroot
+            addStringOption "dac_dataname", project.docs.dac.dataname
         }
     }
 
diff --git a/buildSrc/init.gradle b/buildSrc/init.gradle
index 50e7566..3568446 100644
--- a/buildSrc/init.gradle
+++ b/buildSrc/init.gradle
@@ -34,7 +34,12 @@
 ext.runningInBuildServer = System.env.DIST_DIR != null && System.env.OUT_DIR != null
 
 apply from: "${supportRoot}/buildSrc/dependencies.gradle"
-ext.buildOfflineDocs = rootProject.getProperties().containsKey("offlineDocs")
+ext.docs = [:]
+ext.docs.offline = rootProject.getProperties().containsKey("offlineDocs")
+ext.docs.dac = [
+        libraryroot: "android/support",
+        dataname: "SUPPORT_DATA"
+]
 
 def loadDefaultVersions() {
     apply from: "${supportRootFolder}/buildSrc/versions.gradle"