chore: sampler gets a full context (open-telemetry#1631)

api/src/trace/Sampler.ts

@@ -14,11 +14,11 @@
  * limitations under the License.
  */
 
-import { SpanContext } from './span_context';
-import { SpanKind } from './span_kind';
+import { Context } from '@opentelemetry/context-base';
 import { Attributes } from './attributes';
 import { Link } from './link';
 import { SamplingResult } from './SamplingResult';
+import { SpanKind } from './span_kind';
 
 /**
  * This interface represent a sampler. Sampling is a mechanism to control the
@@ -29,8 +29,7 @@ export interface Sampler {
   /**
    * Checks whether span needs to be created and tracked.
    *
-   * @param parentContext Parent span context. Typically taken from the wire.
-   *     Can be null.
+   * @param context Parent Context which may contain a span.
    * @param traceId of the span to be created. It can be different from the
    *     traceId in the {@link SpanContext}. Typically in situations when the
    *     span to be created starts a new trace.
@@ -42,7 +41,7 @@ export interface Sampler {
    * @returns a {@link SamplingResult}.
    */
   shouldSample(
-    parentContext: SpanContext | undefined,
+    context: Context,
     traceId: string,
     spanName: string,
     spanKind: SpanKind,