Upstream the updated Java Omaha XML parser

chrome/android/java/src/org/chromium/chrome/browser/omaha/XMLParser.java

Index: chrome/android/java/src/org/chromium/chrome/browser/omaha/XMLParser.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/omaha/XMLParser.java b/chrome/android/java/src/org/chromium/chrome/browser/omaha/XMLParser.java
new file mode 100644
index 0000000000000000000000000000000000000000..1e740e7f53cc1cf5ee4091c17eb20fef5f46d097
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/omaha/XMLParser.java
@@ -0,0 +1,104 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.omaha;
+
+import android.text.TextUtils;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+import org.xml.sax.SAXParseException;
+import org.xml.sax.helpers.DefaultHandler;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Stack;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+/**
+ * Breaks XML down into its constituent elements and attributes.
+ */
+public class XMLParser extends DefaultHandler {
+    static final class Node {
+        public final String tag;
+        public final Map<String, String> attributes;
+        public final List<Node> children;
+
+        public Node(String tagName) {
+            tag = tagName;
+            attributes = new HashMap<String, String>();
+            children = new ArrayList<Node>();
+        }
+    }
+
+    private final Node mRootNode;
+    private final Stack<Node> mTagStack;
+
+    public XMLParser(String serverResponse) throws RequestFailureException {
+        mRootNode = new Node(null);
+        mTagStack = new Stack<Node>();
+        mTagStack.push(mRootNode);
+
+        try {
+            SAXParserFactory factory = SAXParserFactory.newInstance();
+            SAXParser saxParser = factory.newSAXParser();
+            saxParser.parse(new InputSource(new StringReader(serverResponse)), this);
+        } catch (IOException e) {
+            throw new RequestFailureException(
+                    "Hit IOException", e, RequestFailureException.ERROR_MALFORMED_XML);
+        } catch (ParserConfigurationException e) {
+            throw new RequestFailureException("Hit ParserConfigurationException", e,
+                    RequestFailureException.ERROR_MALFORMED_XML);
+        } catch (SAXParseException e) {
+            throw new RequestFailureException(
+                    "Hit SAXParseException", e, RequestFailureException.ERROR_MALFORMED_XML);
+        } catch (SAXException e) {
+            throw new RequestFailureException(
+                    "Hit SAXException", e, RequestFailureException.ERROR_MALFORMED_XML);
+        }
+
+        if (mTagStack.peek() != mRootNode) {
+            throw new RequestFailureException(
+                    "XML was malformed.", RequestFailureException.ERROR_MALFORMED_XML);
+        }
+    }
+
+    public Node getRootNode() {
+        return mRootNode;
+    }
+
+    @Override
+    public void startElement(String uri, String localName, String qName, Attributes attributes)
+            throws SAXException {
+        if (mTagStack.empty()) throw new SAXException("Tag stack is empty when it shouldn't be.");
+
+        Node currentNode = new Node(qName);
+        mTagStack.peek().children.add(currentNode);
+        mTagStack.push(currentNode);
+
+        for (int i = 0; i < attributes.getLength(); ++i) {
+            String attributeName = attributes.getLocalName(i);
+            String attributeValue = attributes.getValue(attributeName);
+            currentNode.attributes.put(attributeName, attributeValue);
+        }
+    }
+
+    @Override
+    public void endElement(String uri, String localName, String qName) throws SAXException {
+        if (mTagStack.empty()) {
+            throw new SAXException("Tried closing empty stack with " + qName);
+        } else if (!TextUtils.equals(qName, mTagStack.peek().tag)) {
+            throw new SAXException("Tried closing " + mTagStack.peek().tag + " with " + qName);
+        }
+        mTagStack.pop();
+    }
+}