DevTools: [JsDocValidator] Refactor JsDoc annotation checkers

Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java

Index: Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java
diff --git a/Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java b/Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java
new file mode 100644
index 0000000000000000000000000000000000000000..02a39c07498bdfb91bc98c765ac887c8c4e7f898
--- /dev/null
+++ b/Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java
@@ -0,0 +1,52 @@
+package org.chromium.devtools.jsdoc.checks;
+
+import com.google.javascript.rhino.head.Token;
+import com.google.javascript.rhino.head.ast.AstNode;
+import com.google.javascript.rhino.head.ast.Comment;
+import com.google.javascript.rhino.head.ast.FunctionNode;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public final class RequiredThisAnnotationChecker extends ContextTrackingChecker {
+
+    private final Set<FunctionRecord> functionsRequiringThisAnnotation = new HashSet<>();
+
+    @Override
+    void enterNode(AstNode node) {
+        if (node.getType() == Token.THIS) {
+            FunctionRecord function = getState().getCurrentFunctionRecord();
+            if (function == null) {
+                return;
+            }
+            if (!function.isTopLevelFunction() && !function.isConstructor) {
+                functionsRequiringThisAnnotation.add(function);
+            }
+            return;
+        }
+    }
+
+    @Override
+    void leaveNode(AstNode node) {
+        if (node.getType() != Token.FUNCTION) {
+            return;
+        }
+
+        ContextTrackingState state = getState();
+        FunctionRecord record = state.getCurrentFunctionRecord();
+        if (!functionsRequiringThisAnnotation.contains(record)) {
+            return;
+        }
+        FunctionNode functionNode = (FunctionNode) node;
+        AstNode functionNameNode = AstUtil.getFunctionNameNode(functionNode);
+        if (functionNameNode != null && shouldAddThisAnnotation(functionNode)) {
+            state.getContext().reportErrorInNode(functionNameNode, 0,
+                    "@this annotation is required for functions referencing 'this'");
+        }
+    }
+
+    private boolean shouldAddThisAnnotation(FunctionNode node) {
+        Comment comment = AstUtil.getJsDocNode(node);
+        return comment == null || !getContext().getNodeText(comment).contains("@this");
+    }
+}