Update shelf spacing in Chrome OS according to the MD specs

ash/system/overview/overview_button_tray.cc

Index: ash/system/overview/overview_button_tray.cc
diff --git a/ash/system/overview/overview_button_tray.cc b/ash/system/overview/overview_button_tray.cc
index 4b152b3be601271554d1897d874d83b6f65d3768..043ea9c81a8254e394bfc01b42a4c5317c212a73 100644
--- a/ash/system/overview/overview_button_tray.cc
+++ b/ash/system/overview/overview_button_tray.cc
@@ -4,11 +4,14 @@
 
 #include "ash/system/overview/overview_button_tray.h"
 
+#include "ash/material_design/material_design_controller.h"
 #include "ash/session/session_state_delegate.h"
+#include "ash/shelf/shelf_constants.h"
 #include "ash/shelf/shelf_types.h"
 #include "ash/shelf/shelf_util.h"
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
+#include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_utils.h"
 #include "ash/wm/common/shelf/wm_shelf_util.h"
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
@@ -104,6 +107,27 @@ void OverviewButtonTray::SetShelfAlignment(wm::ShelfAlignment alignment) {
   SetIconBorderForShelfAlignment();
 }
 
+void OverviewButtonTray::GetHitRegionInsets(gfx::Insets& insets) {
+  if (ash::MaterialDesignController::IsShelfMaterial()) {
+    int top_edge, left_edge, bottom_edge, right_edge;
+    if (wm::IsHorizontalAlignment(shelf_alignment())) {
+      top_edge = (GetShelfLayoutConstant(SHELF_SIZE) - kShelfItemHeight) / 2;
+      left_edge = 0;
+      bottom_edge = (GetShelfLayoutConstant(SHELF_SIZE) - kShelfItemHeight) / 2;
+      right_edge = GetTrayConstant(PADDING_FROM_EDGE_OF_SHELF);
+    } else {  // SHELF_ALIGNMENT_LEFT || SHELF_ALIGNMENT_RIGHT
+      top_edge = 0;
+      left_edge = (GetShelfLayoutConstant(SHELF_SIZE) - kShelfItemHeight) / 2;
+      bottom_edge = GetTrayConstant(PADDING_FROM_EDGE_OF_SHELF);
+      right_edge = (GetShelfLayoutConstant(SHELF_SIZE) - kShelfItemHeight) / 2;
+    }
+    insets.Set(top_edge, left_edge, bottom_edge, right_edge);
+  } else {
+    TrayBackgroundView::GetHitRegionInsets(insets);
+  }
+}
+
+// TODO(yiyix): Remove the 3dp border around the button.

[tdanderson, 2016/06/03 19:25:23]

Move to TrayContainer, reword to be something like "TODO(tdanderson|yiyix):
Allow different borders for different buttons, e.g., Overview button should not
have a left border in MD" (as discussed in person). In general TODOs should be
placed nearby the code that eventually needs to be changed.

[yiyix, 2016/06/10 19:26:04]

Done.

 void OverviewButtonTray::SetIconBorderForShelfAlignment() {
   if (wm::IsHorizontalAlignment(shelf_alignment())) {
     icon_->SetBorder(views::Border::CreateEmptyBorder(