Let content_unittests almost build with the components build on android

content/browser/android/browser_jni_registrar.h

Index: content/browser/android/browser_jni_registrar.h
diff --git a/content/browser/android/browser_jni_registrar.h b/content/browser/android/browser_jni_registrar.h
index 03505bb8f23c1207ecc13379837ac6519d8f6033..15f4fb34e10302b7d7d84630a9a691089fb8f8db 100644
--- a/content/browser/android/browser_jni_registrar.h
+++ b/content/browser/android/browser_jni_registrar.h
@@ -7,11 +7,13 @@
 
 #include <jni.h>
 
+#include "content/common/content_export.h"
+
 namespace content {
 namespace android {
 
 // Register all JNI bindings necessary for content browser.
-bool RegisterBrowserJni(JNIEnv* env);
+CONTENT_EXPORT bool RegisterBrowserJni(JNIEnv* env);
 
 }  // namespace android
 }  // namespace content