Fix crash in PDF accessibility when PDF engine reports -1 as char count.

chrome/browser/pdf/pdf_extension_test.cc

Index: chrome/browser/pdf/pdf_extension_test.cc
diff --git a/chrome/browser/pdf/pdf_extension_test.cc b/chrome/browser/pdf/pdf_extension_test.cc
index b63a7bbd46f26361b2d44c443a7b5394e7ab45c1..4e1534d69927b611973e2914248cabec0a6ee043 100644
--- a/chrome/browser/pdf/pdf_extension_test.cc
+++ b/chrome/browser/pdf/pdf_extension_test.cc
@@ -659,6 +659,30 @@ IN_PROC_BROWSER_TEST_F(PDFExtensionTest, PdfAccessibility) {
   ASSERT_MULTILINE_STREQ(kExpectedPDFAXTree, ax_tree_dump);
 }
 
+IN_PROC_BROWSER_TEST_F(PDFExtensionTest, PdfAccessibilityCharCountCrash) {

[raymes, 2017/01/24 23:05:47]

nit: please add a comment with a link to the bug

[dmazzoni, 2017/01/25 20:30:36]

Done.

+  content::BrowserAccessibilityState::GetInstance()->EnableAccessibility();
+
+  GURL test_pdf_url(embedded_test_server()->GetURL(
+      "data:application/pdf;base64,JVBERi0xLjYNCiXi48/TDQo2IDAgb2JqDQo8PA0KL0"
+      "xpbmVhcml6ZWQgMQ0KL0wgMTg2Ng0KL0ggWyA2NTUgMTI3IF0NCi9PIDgNCi9FIDEyMjkN"
+      "Ci9OIDENCi9UIDE2MjANCj4+DQplbmRvYmoNCiAgICAgICAgICAgICAgICAgICAgICAgIC"
+      "AgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICANCnhyZWYNCjYgNg0K"
+      "MDAwMDAwMDAxNyAwMDAwMCBuDQowMDAwMDAwNTg2IDAwMDAwIG4NCjAwMDAwMDA3ODIgMD"
+      "AwMDAgbg0KMDAwMDAwMDk2MyAwMDAwMCBuDQowMDAwMDAxMDQzIDAwMDAwIG4NCjAwMDAw"
+      "MDA2NTUgMDAwMDAgbg0KdHJhaWxlcg0KPDwNCi9TaXplIDEyDQovUHJldiAxNjEwDQovSW"
+      "5mbyA1IDAgUg0KL1Jvb3QgNyAwIFINCi9JRCBbPDZlZjdhODFiZGQ2NDYwMGFmNDQ5NmQ0"
+      "MzMyMjA3ZmViPjw2ZWY3YTgxYmRkNjQ2MDBhZjQ0OTZkNDMzMjIwN2ZlYj5dDQo+Pg0Kc3"
+      "RhcnR4cmVmDQowDQolJUVPRg0KICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg"
+      "ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIC"
+      "AgICAgICAgICAgICAgICAgICAgICAgICAgICANCjcgMCBvYmoNCjw8DQovVHlwZSAvQ2F0"
+      "YWxvZw0KL1BhZ2VzIDEgMCBSDQovTmFtZXMgMiAwIFINCj4+DQplbmRvYmoNCjExIDAgb2"
+      "JqDQo8PA0KL1MgMzYNCi9GaWx0ZXIgL0Zs"));
+  content::WebContents* guest_contents = LoadPdfGetGuestContents(test_pdf_url);
+  ASSERT_TRUE(guest_contents);
+
+  WaitForAccessibilityTreeToContainNodeWithName(guest_contents, "Page 1");
+}
+
 IN_PROC_BROWSER_TEST_F(PDFExtensionTest, PdfAccessibilityEnableLater) {
   // In this test, load the PDF file first, with accessibility off.
   GURL test_pdf_url(embedded_test_server()->GetURL("/pdf/test-bookmarks.pdf"));