Cherry-pick be529425d24e6c7c0cbf6965456da1f2a3a96adf to analyzer-0.33 branch.

This change was intended for 0.33.x version of the analyzer.  It was
landed on master when master was on version 0.33.x and the analyzer
branch was on 0.34.x.  Now that the analyzer branch has been landed,
it needs to be cherry-picked to the analyzer-0.33 branch so that we
can use it to release an update to analyzer 0.33.x.

Original change description:
> Prepare for a future breaking change to the UriResolver class.
>
> See https://dart-review.googlesource.com/c/sdk/+/85726 for the
> breaking change that is anticipated.
>
> Change-Id: I4ba84a0e70bf5b3c62191c053ba9de7aee71ac93
> Reviewed-on: https://dart-review.googlesource.com/c/85728
> Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
> Commit-Queue: Paul Berry <paulberry@google.com>

Change-Id: I6db0d50dc7d342e071c226ae1046f7088ab4ec92
Reviewed-on: https://dart-review.googlesource.com/c/86503
Auto-Submit: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analyzer/CHANGELOG.md b/pkg/analyzer/CHANGELOG.md
index 2f86112..1d0af63 100644
--- a/pkg/analyzer/CHANGELOG.md
+++ b/pkg/analyzer/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.33.6+1-dev
+* Added a note to the `UriResolver` documentation alerting clients of an
+  upcoming breaking change.
+
 ## 0.33.6
 * Deprecated `AstNode.getAncestor` and introduced
   `AstNode.thisOrAncestorMatching` as its replacement.
diff --git a/pkg/analyzer/lib/src/generated/source.dart b/pkg/analyzer/lib/src/generated/source.dart
index 0de7ff4..5c8b4c3 100644
--- a/pkg/analyzer/lib/src/generated/source.dart
+++ b/pkg/analyzer/lib/src/generated/source.dart
@@ -769,6 +769,12 @@
  * The abstract class `UriResolver` defines the behavior of objects that are used to resolve
  * URI's for a source factory. Subclasses of this class are expected to resolve a single scheme of
  * absolute URI.
+ *
+ * NOTICE: in a future breaking change release of the analyzer, a method
+ * `void clearCache()` will be added.  Clients that implement, but do not
+ * extend, this class, can prepare for the breaking change by adding an
+ * implementation of this method that clears any cached URI resolution
+ * information.
  */
 abstract class UriResolver {
   /**
diff --git a/pkg/analyzer/pubspec.yaml b/pkg/analyzer/pubspec.yaml
index 3d34c03..d6cd53d 100644
--- a/pkg/analyzer/pubspec.yaml
+++ b/pkg/analyzer/pubspec.yaml
@@ -1,5 +1,5 @@
 name: analyzer
-version: 0.33.6
+version: 0.33.6+1-dev
 author: Dart Team <misc@dartlang.org>
 description: Static analyzer for Dart.
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/analyzer