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..830c253236d03c3785af0b84beed82d184437a81
--- /dev/null
+++ b/Source/devtools/scripts/jsdoc-validator/src/org/chromium/devtools/jsdoc/checks/RequiredThisAnnotationChecker.java
@@ -0,0 +1,85 @@
+package org.chromium.devtools.jsdoc.checks;
+
+import com.google.javascript.rhino.head.Token;
+import com.google.javascript.rhino.head.ast.Assignment;
+import com.google.javascript.rhino.head.ast.AstNode;
+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 record = getState().getCurrentFunctionRecord();
+            if (record == null) {
+                return;
+            }
+            if (!record.isTopLevelFunction()
+                    && !record.isConstructor
+                    && (hasEnclosingConstructor(record)
+                            || record.enclosingFunctionRecord.enclosingType != null)) {
+                functionsRequiringThisAnnotation.add(record);
+            }
+            return;
+        }
+    }
+
+    private boolean hasEnclosingConstructor(FunctionRecord record) {
+        FunctionRecord parent = record.enclosingFunctionRecord;
+        while (parent != null) {
+            if (parent.isConstructor) {
+                return true;
+            }
+            parent = parent.enclosingFunctionRecord;
+        }
+        return false;
+    }
+
+    @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) {
+        String jsDoc = getJsDoc(node);
+        return jsDoc == null || !jsDoc.contains("@this");
+    }
+
+    private String getJsDoc(FunctionNode functionNode) {
+        String jsDoc = functionNode.getJsDoc();
+        if (jsDoc != null) {
+            return jsDoc;
+        }
+
+        // reader.onloadend = function() {...}
+        if (AstUtil.hasParentOfType(functionNode, Token.ASSIGN)) {
+            Assignment assignment = (Assignment) functionNode.getParent();
+            if (assignment.getRight() == functionNode) {
+                jsDoc = assignment.getJsDoc();
+                if (jsDoc != null) {
+                    return jsDoc;
+                }
+            }
+        }
+        return null;
+    }
+}