Fixes a crash which occurs when a concealed selection handle in a textfield is exposed.

ui/views/touchui/touch_selection_controller_impl_unittest.cc

 // Copyright (c) 2012 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.
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/client/screen_position_client.h"
@@ skipping 163 matching lines @@
           grip_location.x(), grip_location.y(), 0, time_stamp, details);
       handle->OnGestureEvent(&scroll_end);
     }
     test_cursor_client_->EnableMouseEvents();
   }
 
   gfx::NativeView GetCursorHandleNativeView() {
     return GetSelectionController()->GetCursorHandleNativeView();
   }
 
+  ui::SelectionBound::Type GetSelectionHandle1Type() {
+    return GetSelectionController()->GetSelectionHandle1Type();
+  }
+
   gfx::Rect GetSelectionHandle1Bounds() {
     return GetSelectionController()->GetSelectionHandle1Bounds();
   }
 
   gfx::Rect GetSelectionHandle2Bounds() {
     return GetSelectionController()->GetSelectionHandle2Bounds();
   }
 
   gfx::Rect GetCursorHandleBounds() {
     return GetSelectionController()->GetCursorHandleBounds();
@@ skipping 68 matching lines @@
       } else if (CompareTextSelectionBounds(anchor, focus) > 0) {
         EXPECT_EQ(ui::SelectionBound::LEFT, focus.type())  << from_str;
         EXPECT_EQ(ui::SelectionBound::RIGHT, anchor.type())  << from_str;
       } else {
         EXPECT_EQ(ui::SelectionBound::CENTER, focus.type()) << from_str;
         EXPECT_EQ(ui::SelectionBound::CENTER, anchor.type()) << from_str;
       }
     }
   }
 
+  // Sets up a textfield with a long text string such that it doesn't all fit
+  // into the textfield. Then selects the text - the first handle is expected
+  // to be invisible. |selection_start| is the position of the first handle.
+  void SetupSelectionInvisibleHandle(uint32_t selection_start) {
+    // Create a textfield with lots of text in it.
+    CreateTextfield();
+    std::string some_text("some text");
+    std::string textfield_text;
+    for (int i = 0; i < 10; ++i)
+      textfield_text += some_text;
+    textfield_->SetText(ASCIIToUTF16(textfield_text));
+
+    // Tap the textfield to invoke selection.
+    ui::GestureEventDetails details(ui::ET_GESTURE_TAP);
+    details.set_tap_count(1);
+    ui::GestureEvent tap(0, 0, 0, base::TimeDelta(), details);
+    textfield_->OnGestureEvent(&tap);
+
+    // Select some text such that one handle is hidden.
+    textfield_->SelectRange(gfx::Range(
+        selection_start, static_cast<uint32_t>(textfield_text.length())));
+
+    // Check that one selection handle is hidden.
+    EXPECT_FALSE(IsSelectionHandle1Visible());
+    EXPECT_TRUE(IsSelectionHandle2Visible());
+    EXPECT_EQ(gfx::Range(selection_start,
+                         static_cast<uint32_t>(textfield_text.length())),
+              textfield_->GetSelectedRange());
+  }
+
   Widget* textfield_widget_;
   Widget* widget_;
 
   Textfield* textfield_;
   std::unique_ptr<TextfieldTestApi> textfield_test_api_;
   std::unique_ptr<ViewsTouchEditingControllerFactory> views_tsc_factory_;
   std::unique_ptr<aura::test::TestCursorClient> test_cursor_client_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TouchSelectionControllerImplTest);
@@ skipping 250 matching lines @@
 
   // Drag selection handle 2 to right by 1 char.
   x = gfx::Canvas::GetStringWidth(WideToUTF16(L"\x05e2"), font_list);
   SimulateSelectionHandleDrag(gfx::Vector2d(x, 0), 2);
   EXPECT_EQ(WideToUTF16(L"c\x05e1"), textfield_->GetSelectedText());
   VerifyHandlePositions(false, false, FROM_HERE);
 }
 
 TEST_F(TouchSelectionControllerImplTest,
        HiddenSelectionHandleRetainsCursorPosition) {
-  // Create a textfield with lots of text in it.
-  CreateTextfield();
-  std::string textfield_text("some text");
-  for (int i = 0; i < 10; ++i)
-    textfield_text += textfield_text;
-  textfield_->SetText(ASCIIToUTF16(textfield_text));
-
-  // Tap the textfield to invoke selection.
-  ui::GestureEventDetails details(ui::ET_GESTURE_TAP);
-  details.set_tap_count(1);
-  ui::GestureEvent tap(0, 0, 0, base::TimeDelta(), details);
-  textfield_->OnGestureEvent(&tap);
-
-  // Select some text such that one handle is hidden.
-  textfield_->SelectRange(
-      gfx::Range(10u, static_cast<uint32_t>(textfield_text.length())));
-
-  // Check that one selection handle is hidden.
-  EXPECT_FALSE(IsSelectionHandle1Visible());
-  EXPECT_TRUE(IsSelectionHandle2Visible());
-  EXPECT_EQ(
-      gfx::Range(10u, static_cast<uint32_t>(textfield_text.length())),
-      textfield_->GetSelectedRange());
+  static const uint32_t selection_start = 10u;
+  SetupSelectionInvisibleHandle(selection_start);
 
   // Drag the visible handle around and make sure the selection end point of the
   // invisible handle does not change.
   size_t visible_handle_position = textfield_->GetSelectedRange().end();
   for (int i = 0; i < 10; ++i) {
     static const int drag_diff = -10;
     SimulateSelectionHandleDrag(gfx::Vector2d(drag_diff, 0), 2);
     // Make sure that the visible handle is being dragged.
     EXPECT_NE(visible_handle_position, textfield_->GetSelectedRange().end());
     visible_handle_position = textfield_->GetSelectedRange().end();
     EXPECT_EQ((size_t) 10, textfield_->GetSelectedRange().start());
   }
 }
 
+// Tests that we can handle the hidden handle getting exposed as a result of a
+// drag and that it maintains the correct orientation when exposed.
+TEST_F(TouchSelectionControllerImplTest, HiddenSelectionHandleExposed) {
+  static const uint32_t selection_start = 0u;
+  SetupSelectionInvisibleHandle(selection_start);
+
+  // Drag the handle until the selection shrinks such that the other handle
+  // becomes visible.
+  while (!IsSelectionHandle1Visible()) {
+    static const int drag_diff = -10;
+    SimulateSelectionHandleDrag(gfx::Vector2d(drag_diff, 0), 2);
+  }
+
+  // Confirm that the exposed handle maintains the LEFT orientation
+  // (and does not reset to ui::SelectionBound::Type::CENTER).
+  EXPECT_EQ(ui::SelectionBound::Type::LEFT, GetSelectionHandle1Type());
+}
+
 TEST_F(TouchSelectionControllerImplTest,
        DoubleTapInTextfieldWithCursorHandleShouldSelectText) {
   CreateTextfield();
   textfield_->SetText(ASCIIToUTF16("some text"));
   ui::test::EventGenerator generator(
       textfield_->GetWidget()->GetNativeView()->GetRootWindow());
 
   // Tap the textfield to invoke touch selection.
   generator.GestureTapAt(gfx::Point(10, 10));
 
@@ skipping 249 matching lines @@
   // Start touch editing; then press a key and ensure it deactivates touch
   // selection.
   StartTouchEditing();
   EXPECT_TRUE(GetSelectionController());
   generator.PressKey(ui::VKEY_A, 0);
   RunPendingMessages();
   EXPECT_FALSE(GetSelectionController());
 }
 
 }  // namespace views