Mass refactoring: Change JNI #includes to use full paths in example

Using relative paths was causing build failures. Most of base has
already been fixed, this is just fixing the sample/example code.

Bug: 964169
Change-Id: Ief41aca3602ddfa567426147ae60021d6130ad7c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669077
Auto-Submit: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671364}

base/DEPS

 include_rules = [
-  "+jni",
   "+third_party/ashmem",
   "+third_party/apple_apsl",
   "+third_party/boringssl/src/include",

base/android/jni_generator/BUILD.gn

@@ -12,7 +12,6 @@ generate_jni("jni_sample_header") {
     "java/src/org/chromium/example/jni_generator/SampleForAnnotationProcessor.java",
     "java/src/org/chromium/example/jni_generator/SampleForTests.java",
   ]
-  jni_package = "example"
 }
 
 android_library("jni_sample_java") {

base/android/jni_generator/sample_for_tests.cc

@@ -12,8 +12,8 @@
 // Generated file for JNI bindings from C++ to Java @CalledByNative methods.
 // Only to be included in one .cc file.
 // Name is based on the java file name: *.java -> jni/*_jni.h
-#include "jni/SampleForAnnotationProcessor_jni.h"  // Generated by JNI.
-#include "jni/SampleForTests_jni.h"                // Generated by JNI.
+#include "base/android/jni_generator/jni_sample_header/SampleForAnnotationProcessor_jni.h"  // Generated by JNI.
+#include "base/android/jni_generator/jni_sample_header/SampleForTests_jni.h"  // Generated by JNI.
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF8;