exo: Add "back" button to shell surface decorations.

ash/frame/custom_frame_view_ash.cc

Index: ash/frame/custom_frame_view_ash.cc
diff --git a/ash/frame/custom_frame_view_ash.cc b/ash/frame/custom_frame_view_ash.cc
index 90d5c6af3dd921c5e225364a22ecf6446d2d6b4a..dfa1912a4e1c94ad269b8525476db2bccb172cf3 100644
--- a/ash/frame/custom_frame_view_ash.cc
+++ b/ash/frame/custom_frame_view_ash.cc
@@ -8,10 +8,12 @@
 #include <vector>
 
 #include "ash/ash_switches.h"
+#include "ash/frame/caption_buttons/frame_caption_button.h"
 #include "ash/frame/caption_buttons/frame_caption_button_container_view.h"
 #include "ash/frame/default_header_painter.h"
 #include "ash/frame/frame_border_hit_test_controller.h"
 #include "ash/frame/header_painter.h"
+#include "ash/frame/header_painter_util.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_observer.h"
@@ -23,12 +25,14 @@
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
+#include "ui/base/hit_test.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/controls/image_view.h"
+#include "ui/views/layout/box_layout.h"
 #include "ui/views/view.h"
 #include "ui/views/view_targeter.h"
 #include "ui/views/widget/widget.h"
@@ -114,6 +118,39 @@ class CustomFrameViewAshWindowStateDelegate
   DISALLOW_COPY_AND_ASSIGN(CustomFrameViewAshWindowStateDelegate);
 };
 
+class LeftHeaderView : public views::View {
+ public:
+  explicit LeftHeaderView(ash::FrameCaptionButton* caption_button)
+      : caption_button_(caption_button) {
+    SetLayoutManager(
+        new views::BoxLayout(views::BoxLayout::kHorizontal, 0, 0, 0));
+    AddChildView(caption_button_);
+    caption_button_->SetState(views::Button::STATE_NORMAL);
+  }
+  ~LeftHeaderView() override {}
+
+  void SetPaintAsActive(bool active) {
+    caption_button_->set_paint_as_active(active);
+  }
+
+ private:
+  ash::FrameCaptionButton* caption_button_;
+
+  DISALLOW_COPY_AND_ASSIGN(LeftHeaderView);
+};
+
+// Combines View::ConvertPointToTarget() and View::HitTest() for a given
+// |point|. Converts |point| from |src| to |dst| and hit tests it against |dst|.
+bool ConvertedHitTest(views::View* src,
+                      views::View* dst,
+                      const gfx::Point& point) {
+  DCHECK(src);
+  DCHECK(dst);
+  gfx::Point converted_point(point);
+  views::View::ConvertPointToTarget(src, dst, &converted_point);
+  return dst->HitTestPoint(converted_point);
+}
+
 }  // namespace
 
 namespace ash {
@@ -153,6 +190,8 @@ class CustomFrameViewAsh::HeaderView
 
   void SetFrameColors(SkColor active_frame_color, SkColor inactive_frame_color);
 
+  void SetLeftCaptionButton(FrameCaptionButton* left_caption_button);
+
   // views::View:
   void Layout() override;
   void OnPaint(gfx::Canvas* canvas) override;
@@ -170,6 +209,8 @@ class CustomFrameViewAsh::HeaderView
     return avatar_icon_;
   }
 
+  views::View* left_header_view() const { return left_header_view_; }
+
  private:
   // ImmersiveFullscreenController::Delegate:
   void OnImmersiveRevealStarted() override;
@@ -189,6 +230,9 @@ class CustomFrameViewAsh::HeaderView
   // View which contains the window caption buttons.
   FrameCaptionButtonContainerView* caption_button_container_;
 
+  // View which contains the left caption button.
+  LeftHeaderView* left_header_view_;
+
   // The fraction of the header's height which is visible while in fullscreen.
   // This value is meaningless when not in fullscreen.
   double fullscreen_visible_fraction_;
@@ -201,6 +245,7 @@ CustomFrameViewAsh::HeaderView::HeaderView(views::Widget* frame)
       header_painter_(new ash::DefaultHeaderPainter),
       avatar_icon_(NULL),
       caption_button_container_(NULL),
+      left_header_view_(NULL),
       fullscreen_visible_fraction_(0) {
   caption_button_container_ = new FrameCaptionButtonContainerView(frame_);
   caption_button_container_->UpdateSizeButtonVisibility();
@@ -274,18 +319,35 @@ void CustomFrameViewAsh::HeaderView::SetFrameColors(
   header_painter_->SetFrameColors(active_frame_color, inactive_frame_color);
 }
 
+void CustomFrameViewAsh::HeaderView::SetLeftCaptionButton(
+    FrameCaptionButton* left_caption_button) {
+  if (left_header_view_)
+    delete left_header_view_;
+  left_header_view_ = new LeftHeaderView(left_caption_button);
+  AddChildView(left_header_view_);
+  header_painter_->UpdateLeftHeaderView(left_header_view_);
+  Layout();
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // CustomFrameViewAsh::HeaderView, views::View overrides:
 
 void CustomFrameViewAsh::HeaderView::Layout() {
   header_painter_->LayoutHeader();
+  if (left_header_view_) {
+    header_painter_->UpdateLeftViewXInset(0);
+  } else {
+    header_painter_->UpdateLeftViewXInset(
+        ash::HeaderPainterUtil::GetDefaultLeftViewXInset());
+  }
 }
 
 void CustomFrameViewAsh::HeaderView::OnPaint(gfx::Canvas* canvas) {
   bool paint_as_active =
       frame_->non_client_view()->frame_view()->ShouldPaintAsActive();
   caption_button_container_->SetPaintAsActive(paint_as_active);
-
+  if (left_header_view_)
+    left_header_view_->SetPaintAsActive(paint_as_active);
   HeaderPainter::Mode header_mode = paint_as_active ?
       HeaderPainter::MODE_ACTIVE : HeaderPainter::MODE_INACTIVE;
   header_painter_->PaintHeader(canvas, header_mode);
@@ -461,6 +523,11 @@ void CustomFrameViewAsh::SetFrameColors(SkColor active_frame_color,
   header_view_->SetFrameColors(active_frame_color, inactive_frame_color);
 }
 
+void CustomFrameViewAsh::SetLeftCaptionButton(
+    FrameCaptionButton* left_caption_button) {
+  header_view_->SetLeftCaptionButton(left_caption_button);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // CustomFrameViewAsh, views::NonClientFrameView overrides:
 
@@ -478,8 +545,16 @@ gfx::Rect CustomFrameViewAsh::GetWindowBoundsForClientBounds(
 }
 
 int CustomFrameViewAsh::NonClientHitTest(const gfx::Point& point) {
-  return FrameBorderHitTestController::NonClientHitTest(this,
-      header_view_->caption_button_container(), point);
+  int hit_test = FrameBorderHitTestController::NonClientHitTest(
+      this, header_view_->caption_button_container(), point);
+
+  // See if the point is actually within the left header view.
+  if (hit_test == HTCAPTION && header_view_->left_header_view() &&
+      ConvertedHitTest(this, header_view_->left_header_view(), point)) {
+    return HTCLIENT;
+  }
+
+  return hit_test;
 }
 
 void CustomFrameViewAsh::GetWindowMask(const gfx::Size& size,