Make SkOSWindow return the sample count and stencil bit count for its GL context.

include/views/SkOSWindow_Android.h

Index: include/views/SkOSWindow_Android.h
===================================================================
--- include/views/SkOSWindow_Android.h	(revision 7991)
+++ include/views/SkOSWindow_Android.h	(working copy)
@@ -24,7 +24,15 @@
         kNativeGL_BackEndType,
     };
 
-    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */) {
+    struct AttachmentInfo {
+        int fSampleCount;
+        int fStencilBits;
+    };
+
+    bool attach(SkBackEndTypes /* attachType */, int /* msaaSampleCount */, AttachmentInfo* info) {
+        // These are the values requested in SkiaSampleView.java
+        info->fSampleCount = 0;
+        info->fStencilBits = 8;
         return true;
     }
     void detach() {}