Split JNI init so native library preloading dosn't cause native init.

base/android/library_loader/library_loader_hooks.h

Index: base/android/library_loader/library_loader_hooks.h
diff --git a/base/android/library_loader/library_loader_hooks.h b/base/android/library_loader/library_loader_hooks.h
index 3e8969bc59a2c93671bf3e2a4e9d03fefffab096..5c37e6e8880f2e233cef3dbf6ff44a942535d688 100644
--- a/base/android/library_loader/library_loader_hooks.h
+++ b/base/android/library_loader/library_loader_hooks.h
@@ -8,6 +8,7 @@
 #include <jni.h>
 
 #include "base/base_export.h"
+#include "base/callback.h"
 
 namespace base {
 namespace android {
@@ -27,6 +28,11 @@ enum LibraryProcessType {
   PROCESS_WEBVIEW_CHILD = 4,
 };
 
+typedef bool NativeInitializationHook();
+
+BASE_EXPORT void SetNativeInitializationHook(
+    NativeInitializationHook native_initialization_hook);
+
 // Record any pending renderer histogram value as histograms.  Pending values
 // are set by RegisterChromiumAndroidLinkerRendererHistogram and
 // RegisterLibraryPreloaderRendererHistogram.