Handle file additions/removals in ContextDirectoryManager.

pkg/analysis_server/lib/src/resource.dart

Index: pkg/analysis_server/lib/src/resource.dart
diff --git a/pkg/analysis_server/lib/src/resource.dart b/pkg/analysis_server/lib/src/resource.dart
index c01974ceb61a3d54fa096e389c376e5f97ceb3aa..059db1459f25a4ea4a181d6345ef86beebe055ec 100644
--- a/pkg/analysis_server/lib/src/resource.dart
+++ b/pkg/analysis_server/lib/src/resource.dart
@@ -81,6 +81,11 @@ abstract class ResourceProvider {
    * Return the [Resource] that corresponds to the given [path].
    */
   Resource getResource(String path);
+
+  /**
+   * Get the path context used by this resource provider.
+   */
+  Context get pathContext;
 }
 
 
@@ -351,6 +356,9 @@ class MemoryResourceProvider implements ResourceProvider {
     _pathToTimestamp.remove(path);
     _notifyWatchers(path, ChangeType.REMOVE);
   }
+
+  @override
+  Context get pathContext => posix;
 }
 
 
@@ -446,4 +454,7 @@ class PhysicalResourceProvider implements ResourceProvider {
       return new _PhysicalFile(file);
     }
   }
+
+  @override
+  Context get pathContext => io.Platform.isWindows ? windows : posix;
 }