PDF: Fix find text behavior.

Highlight the first search result immediately after finding it while the
search continues onwards. Instead of waiting for all the search results
to return before highlighting the first search result.

BUG=764635

Change-Id: I445ffb88527bd592fc5a51d499ea90d752a88918
Reviewed-on: https://chromium-review.googlesource.com/1013748
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Paul Meyer <paulmeyer@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553843}

pdf/pdfium/findtext_unittest.cc

@@ -167,11 +167,11 @@ TEST_F(FindTextTest, FindText) {
   {
     InSequence sequence;
 
-    for (int i = 0; i < 10; ++i)
+    EXPECT_CALL(client, NotifyNumberOfFindResultsChanged(1, false));
+    EXPECT_CALL(client, NotifySelectedFindResultChanged(0));
+    for (int i = 1; i < 10; ++i)
       EXPECT_CALL(client, NotifyNumberOfFindResultsChanged(i + 1, false));
     EXPECT_CALL(client, NotifyNumberOfFindResultsChanged(10, true));
-
-    EXPECT_CALL(client, NotifySelectedFindResultChanged(_)).Times(0);
   }
 
   engine.StartFind("o", /*case_sensitive=*/true);

pdf/pdfium/pdfium_engine.cc

@@ -2410,6 +2410,7 @@ void PDFiumEngine::StartFind(const std::string& text, bool case_sensitive) {
       character_to_start_searching_from = old_selection[0].char_index();
       last_page_to_search_ = next_page_to_search_;
     }
+    search_in_progress_ = true;
   }
 
   int current_page = next_page_to_search_;
@@ -2449,6 +2450,8 @@ void PDFiumEngine::StartFind(const std::string& text, bool case_sensitive) {
        (pages_.size() > 1 && current_page == next_page_to_search_));
 
   if (end_of_search) {
+    search_in_progress_ = false;
+
     // Send the final notification.
     client_->NotifyNumberOfFindResultsChanged(find_results_.size(), true);
     return;
@@ -2553,6 +2556,7 @@ void PDFiumEngine::SearchUsingICU(const base::string16& term,
 }
 
 void PDFiumEngine::AddFindResult(const PDFiumRange& result) {
+  bool first_result = find_results_.empty();
   // Figure out where to insert the new location, since we could have
   // started searching midway and now we wrapped.
   size_t result_index;
@@ -2568,6 +2572,11 @@ void PDFiumEngine::AddFindResult(const PDFiumRange& result) {
   find_results_.insert(find_results_.begin() + result_index, result);
   UpdateTickMarks();
   client_->NotifyNumberOfFindResultsChanged(find_results_.size(), false);
+  if (first_result) {
+    DCHECK(!resume_find_index_);
+    DCHECK(!current_find_index_);
+    SelectFindResult(/*forward=*/true);
+  }
 }
 
 bool PDFiumEngine::SelectFindResult(bool forward) {
@@ -2631,6 +2640,7 @@ bool PDFiumEngine::SelectFindResult(bool forward) {
   }
 
   client_->NotifySelectedFindResultChanged(current_find_index_.value());
+  if (!search_in_progress_)
     client_->NotifyNumberOfFindResultsChanged(find_results_.size(), true);
   return true;
 }
@@ -2641,6 +2651,7 @@ void PDFiumEngine::StopFind() {
   selecting_ = false;
 
   find_results_.clear();
+  search_in_progress_ = false;
   next_page_to_search_ = -1;
   last_page_to_search_ = -1;
   last_character_index_to_search_ = -1;

pdf/pdfium/pdfium_engine.h

@@ -724,6 +724,8 @@ class PDFiumEngine : public PDFEngine,
   std::string current_find_text_;
   // The results found.
   std::vector<PDFiumRange> find_results_;
+  // Whether a search is in progress.
+  bool search_in_progress_ = false;
   // Which page to search next.
   int next_page_to_search_ = -1;
   // Where to stop searching.