Componentize IgnoreNavigationResourceThrottle and add chrome and webview specific implementations.

android_webview/native/aw_contents.cc

Index: android_webview/native/aw_contents.cc
diff --git a/android_webview/native/aw_contents.cc b/android_webview/native/aw_contents.cc
index 9984b1981bca19777a04ad8847e3f62428d071b8..c2bc8c8a498d5aebf2f7db629db12bfe7e4c8d60 100644
--- a/android_webview/native/aw_contents.cc
+++ b/android_webview/native/aw_contents.cc
@@ -87,6 +87,10 @@ void AwContents::Destroy(JNIEnv* env, jobject obj) {
   delete this;
 }
 
+AwWebContentsDelegate* AwContents::GetAwWebContentsDelegate() const {
+  return web_contents_delegate_.get();
+}
+
 namespace {
 // |message| is passed as base::Owned, so it will automatically be deleted
 // when the callback goes out of scope.