Revert "Android: Switch cast_shell to use implicit JNI registration"

This reverts commit f1854090.

Reason for revert: Causes internal b/120143260.

Change-Id: I83286ee7cb9d5e96e63be66bc47efda802421232
Reviewed-on: https://chromium-review.googlesource.com/c/1354326
Commit-Queue: Alex Leung <alexleung@google.com>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612333}

chromecast/BUILD.gn

@@ -594,6 +594,11 @@ buildflag_header("chromecast_buildflags") {
 }
 
 if (is_android) {
+  generate_jni_registration("cast_shell_jni_registration") {
+    target = ":cast_shell_apk"
+    header_output = "$root_gen_dir/chromecast/android/${target_name}.h"
+  }
+
   android_assets("cast_shell_apk_assets") {
     assert(v8_use_external_startup_data)
 

chromecast/android/BUILD.gn

@@ -15,6 +15,7 @@ cast_shared_library("libcast_shell_android") {
 
   deps = [
     "//base",
+    "//chromecast:cast_shell_jni_registration",
     "//chromecast:cast_shell_lib",
     "//chromecast:chromecast_buildflags",
     "//chromecast/app",
@@ -24,11 +25,25 @@ cast_shared_library("libcast_shell_android") {
     "//chromecast/base:jni_headers",
     "//chromecast/base/metrics",
     "//chromecast/browser",
+    "//components/crash/android:crash_android",
     "//content/public/app:both",
     "//content/public/browser",
     "//skia",
   ]
 
+  # Explicit dependencies required for JNI registration to be able to find the
+  # native side functions.
+  if (is_component_build) {
+    deps += [
+      "//device/bluetooth",
+      "//device/gamepad",
+      "//media/midi",
+      "//ui/android",
+      "//ui/events/devices",
+      "//ui/shell_dialogs",
+    ]
+  }
+
   if (is_cast_using_cma_backend) {
     deps += [ "//chromecast/media/cma/backend/android:cast_media_android" ]
   }

chromecast/app/android/cast_jni_loader.cc

@@ -3,6 +3,9 @@
 // found in the LICENSE file.
 
 #include "base/android/jni_android.h"
+#include "base/android/library_loader/library_loader_hooks.h"
+#include "base/bind.h"
+#include "chromecast/android/cast_shell_jni_registration.h"
 #include "chromecast/app/cast_main_delegate.h"
 #include "content/public/app/content_jni_onload.h"
 #include "content/public/app/content_main.h"
@@ -11,6 +14,10 @@
 // This is called by the VM when the shared library is first loaded.
 JNI_EXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved) {
   base::android::InitVM(vm);
+  JNIEnv* env = base::android::AttachCurrentThread();
+  if (!RegisterMainDexNatives(env) || !RegisterNonMainDexNatives(env)) {
+    return -1;
+  }
 
   if (!content::android::OnJNIOnLoadInit())
     return false;