diff -r 000000000000 -r 6474c204b198 build/annotationProcessors/AnnotationProcessor.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/build/annotationProcessors/AnnotationProcessor.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,161 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.annotationProcessors;
+
+import org.mozilla.gecko.annotationProcessors.classloader.AnnotatableEntity;
+import org.mozilla.gecko.annotationProcessors.classloader.ClassWithOptions;
+import org.mozilla.gecko.annotationProcessors.classloader.IterableJarLoadingURLClassLoader;
+import org.mozilla.gecko.annotationProcessors.utils.GeneratableElementIterator;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Iterator;
+
+public class AnnotationProcessor {
+    public static final String OUTFILE = "GeneratedJNIWrappers.cpp";
+    public static final String HEADERFILE = "GeneratedJNIWrappers.h";
+
+    public static final String GENERATED_COMMENT =
+            "// GENERATED CODE\n" +
+            "// Generated by the Java program at /build/annotationProcessors at compile time from\n" +
+            "// annotations on Java methods. To update, change the annotations on the corresponding Java\n" +
+            "// methods and rerun the build. Manually updating this file will cause your build to fail.\n\n";
+
+    public static void main(String[] args) {
+        // We expect a list of jars on the commandline. If missing, whinge about it.
+        if (args.length <= 1) {
+            System.err.println("Usage: java AnnotationProcessor jarfiles ...");
+            System.exit(1);
+        }
+
+        System.out.println("Processing annotations...");
+
+        // We want to produce the same output as last time as often as possible. Ordering of
+        // generated statements, therefore, needs to be consistent.
+        Arrays.sort(args);
+
+        // Start the clock!
+        long s = System.currentTimeMillis();
+
+        // Get an iterator over the classes in the jar files given...
+        Iterator<ClassWithOptions> jarClassIterator = IterableJarLoadingURLClassLoader.getIteratorOverJars(args);
+
+        StringBuilder headerFile = new StringBuilder(GENERATED_COMMENT);
+        headerFile.append("#ifndef GeneratedJNIWrappers_h__\n" +
+                          "#define GeneratedJNIWrappers_h__\n\n" +
+                          "#include \"nsXPCOMStrings.h\"\n" +
+                          "#include \"AndroidJavaWrappers.h\"\n" +
+                          "\n" +
+                          "namespace mozilla {\n" +
+                          "namespace widget {\n" +
+                          "namespace android {\n" +
+                          "void InitStubs(JNIEnv *jEnv);\n\n");
+
+        StringBuilder implementationFile = new StringBuilder(GENERATED_COMMENT);
+        implementationFile.append("#include \"GeneratedJNIWrappers.h\"\n" +
+                                  "#include \"AndroidBridgeUtilities.h\"\n" +
+                                  "#include \"nsXPCOMStrings.h\"\n" +
+                                  "#include \"AndroidBridge.h\"\n" +
+                                  "\n" +
+                                  "namespace mozilla {\n" +
+                                  "namespace widget {\n" +
+                                  "namespace android {\n");
+
+        // Used to track the calls to the various class-specific initialisation functions.
+        StringBuilder stubInitialiser = new StringBuilder();
+        stubInitialiser.append("void InitStubs(JNIEnv *jEnv) {\n");
+
+        while (jarClassIterator.hasNext()) {
+            ClassWithOptions aClassTuple = jarClassIterator.next();
+
+            CodeGenerator generatorInstance;
+
+            // Get an iterator over the appropriately generated methods of this class
+            Iterator<AnnotatableEntity> methodIterator = new GeneratableElementIterator(aClassTuple.wrappedClass);
+
+            if (!methodIterator.hasNext()) {
+                continue;
+            }
+            generatorInstance = new CodeGenerator(aClassTuple.wrappedClass, aClassTuple.generatedName);
+
+            stubInitialiser.append("    ").append(aClassTuple.generatedName).append("::InitStubs(jEnv);\n");
+
+            // Iterate all annotated members in this class..
+            while (methodIterator.hasNext()) {
+                AnnotatableEntity aElementTuple = methodIterator.next();
+                switch (aElementTuple.mEntityType) {
+                    case METHOD:
+                        generatorInstance.generateMethod(aElementTuple);
+                        break;
+                    case FIELD:
+                        generatorInstance.generateField(aElementTuple);
+                        break;
+                    case CONSTRUCTOR:
+                        generatorInstance.generateConstructor(aElementTuple);
+                        break;
+                }
+            }
+
+            headerFile.append(generatorInstance.getHeaderFileContents());
+            implementationFile.append(generatorInstance.getWrapperFileContents());
+        }
+
+        implementationFile.append('\n');
+        stubInitialiser.append("}");
+        implementationFile.append(stubInitialiser);
+
+        implementationFile.append("\n} /* android */\n" +
+                                    "} /* widget */\n" +
+                                    "} /* mozilla */\n");
+
+        headerFile.append("\n} /* android */\n" +
+                            "} /* widget */\n" +
+                            "} /* mozilla */\n" +
+                            "#endif\n");
+
+        writeOutputFiles(headerFile, implementationFile);
+        long e = System.currentTimeMillis();
+        System.out.println("Annotation processing complete in " + (e - s) + "ms");
+    }
+
+    private static void writeOutputFiles(StringBuilder aHeaderFile, StringBuilder aImplementationFile) {
+        FileOutputStream headerStream = null;
+        try {
+            headerStream = new FileOutputStream(OUTFILE);
+            headerStream.write(aImplementationFile.toString().getBytes());
+        } catch (IOException e) {
+            System.err.println("Unable to write " + OUTFILE + ". Perhaps a permissions issue?");
+            e.printStackTrace(System.err);
+        } finally {
+            if (headerStream != null) {
+                try {
+                    headerStream.close();
+                } catch (IOException e) {
+                    System.err.println("Unable to close headerStream due to "+e);
+                    e.printStackTrace(System.err);
+                }
+            }
+        }
+
+        FileOutputStream outStream = null;
+        try {
+            outStream = new FileOutputStream(HEADERFILE);
+            outStream.write(aHeaderFile.toString().getBytes());
+        } catch (IOException e) {
+            System.err.println("Unable to write " + HEADERFILE + ". Perhaps a permissions issue?");
+            e.printStackTrace(System.err);
+        } finally {
+            if (outStream != null) {
+                try {
+                    outStream.close();
+                } catch (IOException e) {
+                    System.err.println("Unable to close outStream due to "+e);
+                    e.printStackTrace(System.err);
+                }
+            }
+        }
+    }
+}
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