Align the base of the shelf's context menu to the top edge of the shelf.

ash/shelf/shelf_view.cc

Index: ash/shelf/shelf_view.cc
diff --git a/ash/shelf/shelf_view.cc b/ash/shelf/shelf_view.cc
index 41a6a5206217593370df8e867666ea992d0d567e..f57d53aef0c0dc3f545dd9ef7ded00f8463bbeae 100644
--- a/ash/shelf/shelf_view.cc
+++ b/ash/shelf/shelf_view.cc
@@ -26,6 +26,7 @@
 #include "ash/shell_port.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/wm/root_window_finder.h"
+#include "ash/wm/wm_screen_util.h"
 #include "ash/wm_window.h"
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
@@ -1600,11 +1601,33 @@ void ShelfView::AfterItemSelected(
 void ShelfView::ShowContextMenuForView(views::View* source,
                                        const gfx::Point& point,
                                        ui::MenuSourceType source_type) {
+  WmWindow* shelf_window = WmWindow::Get(shelf_widget_->GetNativeWindow());

[msw, 2017/05/05 17:34:18]

nit: add a comment to this block of code, like "Align the context menu to the
edge of the shelf."

[minch1, 2017/05/08 17:21:02]

Done.

+  gfx::Rect shelf_bounds =
+      is_overflow_mode()
+          ? (owner_overflow_bubble_->bubble_view()->GetBubbleBounds())
+          : (wm::GetDisplayBoundsInParent(shelf_window));

[msw, 2017/05/05 17:34:18]

You'll probably need to refactor this as per
https://codereview.chromium.org/2860163005/

+
+  gfx::Point point_aligned_shelf;

[msw, 2017/05/05 17:34:18]

nit: consider |menu_point| or |context_menu_point|.

[minch1, 2017/05/08 17:21:02]

Done.

+  switch (wm_shelf_->GetAlignment()) {
+    case SHELF_ALIGNMENT_BOTTOM:
+    case SHELF_ALIGNMENT_BOTTOM_LOCKED:
+      point_aligned_shelf.SetPoint(point.x(),
+                                   shelf_bounds.bottom() - kShelfSize);

[msw, 2017/05/05 17:34:19]

Why not just use shelf_bounds.y()?

[minch1, 2017/05/08 17:21:02]

This is fine for overflow mode, if it is not. The shelf_bounds actually is the
whole screen, left point of the Rect is (0, 0) with the screen's width and
height.
So, here if use shelf_bounds.y(), it will be 0 for none overflow mode. Then, the
context menu will shown on the top of the screen.

+      break;
+    case SHELF_ALIGNMENT_LEFT:
+      point_aligned_shelf.SetPoint(shelf_bounds.x() + kShelfSize, point.y());

[msw, 2017/05/05 17:34:19]

Ditto: why not just use shelf_bounds.right()?

+      break;
+    case SHELF_ALIGNMENT_RIGHT:
+      point_aligned_shelf.SetPoint(shelf_bounds.right() - kShelfSize,

[msw, 2017/05/05 17:34:19]

Ditto: why not just use shelf_bounds.x()?

+                                   point.y());
+    default:

[msw, 2017/05/05 17:34:19]

Remove the default case, so if anyone adds a new alignment they'll update this
switch.

+      break;
+  }
   last_pressed_index_ = -1;
 
   const ShelfItem* item = ShelfItemForView(source);
   if (!item) {
-    ShellPort::Get()->ShowContextMenu(point, source_type);
+    ShellPort::Get()->ShowContextMenu(point_aligned_shelf, source_type);
     return;
   }
 
@@ -1614,8 +1637,8 @@ void ShelfView::ShowContextMenuForView(views::View* source,
     return;
 
   context_menu_id_ = item ? item->id : 0;
-  ShowMenu(std::move(context_menu_model), source, point, true, source_type,
-           nullptr);
+  ShowMenu(std::move(context_menu_model), source, point_aligned_shelf, true,
+           source_type, nullptr);
 }
 
 void ShelfView::ShowMenu(std::unique_ptr<ui::MenuModel> menu_model,
@@ -1644,6 +1667,7 @@ void ShelfView::ShowMenu(std::unique_ptr<ui::MenuModel> menu_model,
   views::MenuAnchorPosition menu_alignment = views::MENU_ANCHOR_TOPLEFT;
   gfx::Rect anchor = gfx::Rect(click_point, gfx::Size());
 
+  ShelfAlignment shelf_alignment = wm_shelf_->GetAlignment();
   if (!context_menu) {
     // Application lists use a bubble.
     // It is possible to invoke the menu while it is sliding into view. To cover
@@ -1656,7 +1680,7 @@ void ShelfView::ShowMenu(std::unique_ptr<ui::MenuModel> menu_model,
       anchor.Inset(source->border()->GetInsets());
 
     // Determine the menu alignment dependent on the shelf.
-    switch (wm_shelf_->GetAlignment()) {
+    switch (shelf_alignment) {
       case SHELF_ALIGNMENT_BOTTOM:
       case SHELF_ALIGNMENT_BOTTOM_LOCKED:
         menu_alignment = views::MENU_ANCHOR_BUBBLE_ABOVE;
@@ -1670,6 +1694,13 @@ void ShelfView::ShowMenu(std::unique_ptr<ui::MenuModel> menu_model,
     }
   }
 
+  // Distinguish the touch events that triggered on the bottom shelf or
+  // left / right shelf. Since they should have different |MenuAnchorPosition|.
+  if (source_type == ui::MENU_SOURCE_TOUCH &&
+      (shelf_alignment == SHELF_ALIGNMENT_LEFT ||

[msw, 2017/05/05 17:34:18]

Use !WmShelf::IsHorizontalAlignment() instead, and remove the |shelf_alignment|
local.

+       shelf_alignment == SHELF_ALIGNMENT_RIGHT)) {
+    source_type = ui::MENU_SOURCE_TOUCH_SIDE_SHELF;
+  }
   // NOTE: if you convert to HAS_MNEMONICS be sure to update menu building code.
   launcher_menu_runner_->RunMenuAt(source->GetWidget(), nullptr, anchor,
                                    menu_alignment, source_type);
@@ -1756,7 +1787,7 @@ bool ShelfView::CanPrepareForDrag(Pointer pointer,
     return false;
   }
 
-  // Touch dragging only begins after a dealy from the press event. This
+  // Touch dragging only begins after a delay from the press event. This
   // prevents accidental dragging on swipe or scroll gestures.
   if (pointer == TOUCH &&
       (base::TimeTicks::Now() - touch_press_time_) <