Find-in-page should not ding while deleting characters.

BUG=18120
TEST=Open google.com, type Ctrl+F, type in garbage. Erase one letter at a time and there should be no beeping while you erase. Try it again, but this time use shift-delete to cut a few letters off the end. It should not ding. Now Copy the whole find string, press Esc, open Find again and on Paste it should not ding.

Review URL: http://codereview.chromium.org/338005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30092 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/find_bar_controller.cc

@@ -121,7 +121,10 @@ void FindBarController::Observe(NotificationType type,
       UpdateFindBarForCurrentResult();
       if (tab_contents_->find_result().final_update() &&
           tab_contents_->find_result().number_of_matches() == 0) {
-        find_bar_->AudibleAlert();
+        const string16& last_search = tab_contents_->previous_find_text();
+        const string16& current_search = tab_contents_->find_text();
+        if (last_search.find(current_search) != 0)
+          find_bar_->AudibleAlert();
       }
     }
   } else if (type == NotificationType::NAV_ENTRY_COMMITTED) {

chrome/browser/tab_contents/tab_contents.cc

@@ -1084,6 +1084,9 @@ void TabContents::StartFinding(string16 find_text,
     find_text = *last_search_prepopulate_text_;
   }
 
+  // Keep track of the previous search.
+  previous_find_text_ = find_text_;
+
   // This is a FindNext operation if we are searching for the same text again,
   // or if the passed in search text is empty (FindNext keyboard shortcut). The
   // exception to this is if the Find was aborted (then we don't want FindNext
@@ -1117,6 +1120,7 @@ void TabContents::StopFinding(bool clear_selection) {
   // by the user, but the UI has not been dismissed.
   if (!clear_selection)
     find_ui_active_ = false;
+  find_text_.clear();
   find_op_aborted_ = true;
   last_search_result_ = FindNotificationDetails();
   render_view_host()->StopFinding(clear_selection);

chrome/browser/tab_contents/tab_contents.h

@@ -530,6 +530,9 @@ class TabContents : public PageNavigator,
   // active searches.
   string16 find_text() const { return find_text_; }
 
+  // Accessor for the previous search we issued.
+  string16 previous_find_text() const { return previous_find_text_; }
+
   // Accessor for last_search_prepopulate_text_. Used to access the last search
   // string entered, whatever tab that search was performed in.
   string16 find_prepopulate_text() const {
@@ -1105,10 +1108,14 @@ class TabContents : public PageNavigator,
   // This variable keeps track of what the most recent request id is.
   int current_find_request_id_;
 
-  // The last string we searched for. This is used to figure out if this is a
-  // Find or a FindNext operation (FindNext should not increase the request id).
+  // The current string we are/just finished searching for. This is used to
+  // figure out if this is a Find or a FindNext operation (FindNext should not
+  // increase the request id).
   string16 find_text_;
 
+  // The string we searched for before |find_text_|.
+  string16 previous_find_text_;
+
   // Whether the last search was case sensitive or not.
   bool last_search_case_sensitive_;