Fix assertion failure in range.mm while examining system dictionary popup.

chrome/browser/renderer_host/text_input_client_mac_unittest.mm

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/renderer_host/text_input_client_mac.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 #include "base/threading/thread.h"
 #include "chrome/common/text_input_client_messages.h"
@@ skipping 88 matching lines @@
 
 TEST_F(TextInputClientMacTest, TimeoutCharacterIndex) {
   NSUInteger index = service()->GetCharacterIndexAtPoint(
       widget(), gfx::Point(2, 2));
   EXPECT_EQ(1U, ipc_sink().message_count());
   EXPECT_TRUE(ipc_sink().GetUniqueMessageMatching(
       TextInputClientMsg_CharacterIndexForPoint::ID));
   EXPECT_EQ(NSNotFound, index);
 }
 
+TEST_F(TextInputClientMacTest, NotFoundCharacterIndex) {
+  ScopedTestingThread thread(this);
+  const NSUInteger kNotFoundValue = static_cast<NSUInteger>(-1);
+
+  PostTask(base::Bind(&TextInputClientMac::SetCharacterIndexAndSignal,
+      base::Unretained(service()), kNotFoundValue));
+  NSUInteger index = service()->GetCharacterIndexAtPoint(
+      widget(), gfx::Point(2, 2));
+
+  EXPECT_EQ(1U, ipc_sink().message_count());
+  EXPECT_TRUE(ipc_sink().GetUniqueMessageMatching(
+      TextInputClientMsg_CharacterIndexForPoint::ID));
+  EXPECT_EQ(NSNotFound, index);
+}
+
 TEST_F(TextInputClientMacTest, GetRectForRange) {
   ScopedTestingThread thread(this);
   const NSRect kSuccessValue = NSMakeRect(42, 43, 44, 45);
 
   PostTask(base::Bind(&TextInputClientMac::SetFirstRectAndSignal,
       base::Unretained(service()), kSuccessValue));
   NSRect rect = service()->GetFirstRectForRange(widget(), NSMakeRange(0, 32));
 
   EXPECT_EQ(1U, ipc_sink().message_count());
   EXPECT_TRUE(ipc_sink().GetUniqueMessageMatching(
@@ skipping 33 matching lines @@
 TEST_F(TextInputClientMacTest, TimeoutSubstring) {
   NSAttributedString* string = service()->GetAttributedSubstringFromRange(
       widget(), NSMakeRange(0, 32));
   EXPECT_EQ(nil, string);
   EXPECT_EQ(1U, ipc_sink().message_count());
   EXPECT_TRUE(ipc_sink().GetUniqueMessageMatching(
       TextInputClientMsg_StringForRange::ID));
 }
 
 }  // namespace