Implement a shell of FindRequestManager, and hook it up to WebContentsImpl.

android_webview/browser/find_helper.cc

Index: android_webview/browser/find_helper.cc
diff --git a/android_webview/browser/find_helper.cc b/android_webview/browser/find_helper.cc
index 7eebbf22587c3fe2354498793f09b99727d7e241..8fc9979f607e3dbe782cf4120a199924977a3466 100644
--- a/android_webview/browser/find_helper.cc
+++ b/android_webview/browser/find_helper.cc
@@ -39,7 +39,7 @@ void FindHelper::FindAllAsync(const base::string16& search_string) {
 
   async_find_started_ = true;
 
-  StartNewRequest(search_string);
+  StartNewSession(search_string);
 
   if (MaybeHandleEmptySearch(search_string))
     return;
@@ -66,6 +66,8 @@ void FindHelper::FindNext(bool forward) {
   if (!async_find_started_)
     return;
 
+  current_request_id_ = find_request_id_counter_++;
+
   if (MaybeHandleEmptySearch(last_search_string_))
     return;
 
@@ -95,7 +97,7 @@ bool FindHelper::MaybeHandleEmptySearch(const base::string16& search_string) {
   return true;
 }
 
-void FindHelper::StartNewRequest(const base::string16& search_string) {
+void FindHelper::StartNewSession(const base::string16& search_string) {
   current_request_id_ = find_request_id_counter_++;
   last_search_string_ = search_string;
   last_match_count_ = -1;