Allow offset for secondary display position in chrome://settings/display.

ash/display/display_controller.cc

Index: ash/display/display_controller.cc
diff --git a/ash/display/display_controller.cc b/ash/display/display_controller.cc
index a4eceb48bb21abb1c6697eb46ab5557eebcdd370..f532860b9a4fcbbc87e28f424a28ab270a58c720 100644
--- a/ash/display/display_controller.cc
+++ b/ash/display/display_controller.cc
@@ -23,7 +23,8 @@ namespace ash {
 namespace internal {
 
 DisplayController::DisplayController()
-    : secondary_display_layout_(RIGHT) {
+    : secondary_display_layout_(RIGHT),
+      secondary_display_offset_(0) {
   aura::Env::GetInstance()->display_manager()->AddObserver(this);
 }
 
@@ -120,6 +121,11 @@ void DisplayController::SetSecondaryDisplayLayout(
   UpdateDisplayBoundsForLayout();
 }
 
+void DisplayController::SetSecondaryDisplayOffset(int offset) {
+  secondary_display_offset_ = offset;
+  UpdateDisplayBoundsForLayout();
+}
+
 bool DisplayController::WarpMouseCursorIfNecessary(
     aura::RootWindow* current_root,
     const gfx::Point& point_in_root) {
@@ -235,18 +241,29 @@ void DisplayController::UpdateDisplayBoundsForLayout() {
   gfx::Point new_secondary_origin = primary_bounds.origin();
 
   // TODO(oshima|mukai): Implement more flexible layout.
+
+  // Ignore the offset in case that the secondary display doesn't share edges
+  // with the primary display.
+  int offset = secondary_display_layout_;
+  if (secondary_display_layout_ == TOP || secondary_display_layout_ == BOTTOM) {
+    if (offset > primary_bounds.width() || offset < -secondary_bounds.width())
+      offset = 0;

[oshima_google, 2012/08/06 05:44:37]

I think it's better to adjust the offset (just keep 10~50 pixels), instead of
ignoring them.

[Jun Mukai, 2012/08/06 06:58:35]

Done.

+  } else {
+    if (offset > primary_bounds.height() || offset < -secondary_bounds.height())
+      offset = 0;
+  }
   switch (secondary_display_layout_) {
     case TOP:
-      new_secondary_origin.Offset(0, -secondary_bounds.height());
+      new_secondary_origin.Offset(offset, -secondary_bounds.height());
       break;
     case RIGHT:
-      new_secondary_origin.Offset(primary_bounds.width(), 0);
+      new_secondary_origin.Offset(primary_bounds.width(), offset);
       break;
     case BOTTOM:
-      new_secondary_origin.Offset(0, primary_bounds.height());
+      new_secondary_origin.Offset(offset, primary_bounds.height());
       break;
     case LEFT:
-      new_secondary_origin.Offset(-secondary_bounds.width(), 0);
+      new_secondary_origin.Offset(-secondary_bounds.width(), offset);
       break;
   }
   gfx::Insets insets = secondary_display->GetWorkAreaInsets();