touchui: Fine-tune selection-controller visibility.

views/touchui/touch_selection_controller_impl.cc

Index: views/touchui/touch_selection_controller_impl.cc
diff --git a/views/touchui/touch_selection_controller_impl.cc b/views/touchui/touch_selection_controller_impl.cc
index 0de16ce8dec7d1187b42f116d9791469943a63dc..87cee31bf95c0fe1f344b49e75526bbc047010da 100644
--- a/views/touchui/touch_selection_controller_impl.cc
+++ b/views/touchui/touch_selection_controller_impl.cc
@@ -31,6 +31,9 @@ const int kSelectionHandleAlpha = 0x7F;
 const SkColor kSelectionHandleColor =
     SkColorSetA(SK_ColorBLUE, kSelectionHandleAlpha);
 
+// The minimum selection size to trigger selection controller.
+const int kMinSelectionSize = 4;
+
 const int kContextMenuCommands[] = {IDS_APP_CUT,
                                     IDS_APP_COPY,
 // TODO(varunjain): PASTE is acting funny due to some gtk clipboard issue.
@@ -279,8 +282,13 @@ void TouchSelectionControllerImpl::SelectionChanged(const gfx::Point& p1,
   } else {
     UpdateContextMenu(p1, p2);
 
-    // Check if there is any selection at all.
-    if (screen_pos_1 == screen_pos_2) {
+    // Check if there is any selection at all. The points may not match exactly,
+    // since the selection range computation may introduce some floating point
+    // errors. So check for a minimum size to decide whether or not there is any
+    // selection.
+    int delta_x = screen_pos_2.x() - screen_pos_1.x();
+    int delta_y = screen_pos_2.y() - screen_pos_1.y();
+    if (abs(delta_x) < kMinSelectionSize && abs(delta_y) < kMinSelectionSize) {
       selection_handle_1_->SetVisible(false);
       selection_handle_2_->SetVisible(false);
       return;