Introduce base classes for blame contexts

tracing/tracing/core/test_utils.html

Index: tracing/tracing/core/test_utils.html
diff --git a/tracing/tracing/core/test_utils.html b/tracing/tracing/core/test_utils.html
index db9a59c7fcd5bd48edcdb93f1ac5ceb0802cf836..a21fb014904273277503da5bd7050716a8399d76 100644
--- a/tracing/tracing/core/test_utils.html
+++ b/tracing/tracing/core/test_utils.html
@@ -9,6 +9,7 @@ found in the LICENSE file.
 <link rel="import" href="/tracing/importer/import.html">
 <link rel="import" href="/tracing/model/counter.html">
 <link rel="import" href="/tracing/model/model.html">
+<link rel="import" href="/tracing/model/scoped_id.html">
 <link rel="import" href="/tracing/model/slice.html">
 <link rel="import" href="/tracing/model/slice_group.html">
 <link rel="import" href="/tracing/model/stack_frame.html">
@@ -268,6 +269,17 @@ tr.exportTo('tr.c', function() {
     return frame;
   };
 
+  TestUtils.newSnapshot = function(model, options) {
+    return model.getOrCreateProcess(options.pid || 1).objects.addSnapshot(
+        new tr.model.ScopedId(options.scope || tr.model.OBJECT_DEFAULT_SCOPE,
+                              options.id || '0x1'),
+        options.category || 'cat',
+        options.name || 'A',
+        options.ts || 0,
+        options.args || {},
+        options.baseTypeName);
+  };
+
   TestUtils.findSliceNamed = function(slices, name) {
     if (slices instanceof tr.model.SliceGroup)
       slices = slices.slices;