Update jni_generator documentation removing GYP.

base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java

Index: base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java
diff --git a/base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java b/base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java
index aaa37de6ebbe762610c13134d964a83040891547..4958f04f619e4aeacae528d6cc80ef287987a6d0 100644
--- a/base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java
+++ b/base/android/jni_generator/java/src/org/chromium/example/jni_generator/SampleForTests.java
@@ -19,7 +19,7 @@ import java.util.List;
 // This class serves as a reference test for the bindings generator, and as example documentation
 // for how to use the jni generator.
 // The C++ counter-part is sample_for_tests.cc.
-// jni_generator.gyp has a jni_generator_tests target that will:
+// jni_generator/BUILD.gn has a jni_generator_tests target that will:
 //   * Generate a header file for the JNI bindings based on this file.
 //   * Compile sample_for_tests.cc using the generated header file.
 //   * link a native executable to prove the generated header + cc file are self-contained.