Don't select empty PDF pages when "Select All" is requested.

`PDFiumEngine::SelectAll` selected all pages regardless of having text
or not, while `PDFiumEngine::Selection` only selects pages in the given
range that include text.
To make the behavior consistent, update the former to only select pages
with text.


Bug: 387387738, 392926460
Change-Id: Iee4833d7b44acc8e5ef7175560f77de0b4a1ed25
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6218255
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1414767}

pdf/pdfium/pdfium_engine.cc

@@ -1759,7 +1759,9 @@ bool PDFiumEngine::ExtendSelection(int page_index, int char_index) {
     // First make sure that there are no gaps in selection, i.e. if mousedown on
     // page one but we only get mousemove over page three, we want page two.
     for (int i = last_page_index + 1; i < page_index; ++i) {
-      selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
+      if (pages_[i]->GetCharCount()) {
+        selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
+      }
     }
 
     int count = pages_[last_page_index]->GetCharCount();
@@ -1775,7 +1777,9 @@ bool PDFiumEngine::ExtendSelection(int page_index, int char_index) {
     // First make sure that there are no gaps in selection, i.e. if mousedown on
     // page three but we only get mousemove over page one, we want page two.
     for (int i = last_page_index - 1; i > page_index; --i) {
-      selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
+      if (pages_[i]->GetCharCount()) {
+        selection_.push_back(PDFiumRange::AllTextOnPage(pages_[i].get()));
+      }
     }
 
     int count = pages_[page_index]->GetCharCount();
@@ -2433,7 +2437,7 @@ void PDFiumEngine::SelectAll() {
 
   selection_.clear();
   for (const auto& page : pages_) {
-    if (page->available()) {
+    if (page->GetCharCount()) {
       selection_.push_back(PDFiumRange::AllTextOnPage(page.get()));
     }
   }

pdf/pdfium/pdfium_on_demand_searchifier_unittest.cc

@@ -517,6 +517,40 @@ TEST_P(PDFiumOnDemandSearchifierTest, MetricsCanceledPageWithoutText) {
   histogram_tester.ExpectTotalCount(kSearchifyAddedTextHistogram, 0);
 }
 
+TEST_P(PDFiumOnDemandSearchifierTest, SelectPageBeforeSearchify) {
+  CreateEngine(FILE_PATH_LITERAL("image_alt_text.pdf"));
+
+  PDFiumPage& page = GetPDFiumPageForTest(*engine(), 0);
+
+  // Load the page to trigger searchify checking.
+  page.GetPage();
+  ASSERT_TRUE(engine()->PageNeedsSearchify(0));
+  engine()->SelectAll();
+  ASSERT_TRUE(engine()->GetSelectedText().empty());
+
+  PDFiumOnDemandSearchifier* searchifier = engine()->GetSearchifierForTesting();
+  ASSERT_TRUE(searchifier);
+
+  ASSERT_TRUE(searchifier->IsPageScheduled(0));
+
+  StartSearchify(/*empty_results=*/false);
+
+  base::test::TestFuture<void> future;
+  WaitUntilIdle(searchifier, future.GetCallback());
+  ASSERT_TRUE(future.Wait());
+
+  // Perform SelectAll again to select extracted text.
+  engine()->SelectAll();
+
+  // The page has 2 images, so the text contains 2 fake OCR results.
+#if BUILDFLAG(IS_WIN)
+  const char kExpectedSelection[] = "OCR Text 0\r\nOCR Text 1";
+#else
+  const char kExpectedSelection[] = "OCR Text 0\nOCR Text 1";
+#endif
+  ASSERT_EQ(engine()->GetSelectedText(), kExpectedSelection);
+}
+
 INSTANTIATE_TEST_SUITE_P(All, PDFiumOnDemandSearchifierTest, testing::Bool());
 
 }  // namespace chrome_pdf