Refactor BrowserViewRenderer to support page visibility

android_webview/native/aw_contents.h

Index: android_webview/native/aw_contents.h
diff --git a/android_webview/native/aw_contents.h b/android_webview/native/aw_contents.h
index 9e03a32229dcac17337d4f44860968114a3d14ec..2b4adc534494ee762f02e384b91f00a9177e9a0e 100644
--- a/android_webview/native/aw_contents.h
+++ b/android_webview/native/aw_contents.h
@@ -117,6 +117,7 @@ class AwContents : public FindHelper::Listener,
   void OnDetachedFromWindow(JNIEnv* env, jobject obj);
   base::android::ScopedJavaLocalRef<jbyteArray> GetOpaqueState(
       JNIEnv* env, jobject obj);
+  bool IsVisible(JNIEnv* env, jobject obj);
   jboolean RestoreFromOpaqueState(JNIEnv* env, jobject obj, jbyteArray state);
   void FocusFirstNode(JNIEnv* env, jobject obj);
   void SetBackgroundColor(JNIEnv* env, jobject obj, jint color);