Mash: Show app icons in shelf based on the Widget's app icon

* Use the large icon from WidgetDelegate::GetWindowAppIcon().
* In the mojo app's NativeWidgetMus, serialize the icon's SkBitmap as a vector of bytes and set it as a shared window property.
* In the window manager, pass the serialized icon to any UserWindowObservers.
* In the system UI, deserialize the icon and use it on the shelf.
* Set an icon in task_viewer as a demonstration.

The window property serialization is handled by a custom TypeConverter for vector<uint8>, SkBitmap. In the future it would be nice to use the serialized form of the Skia Mojom struct skia.Bitmap, but that will require Mojo to generate a public API to read the serialized bytes.

Also fixed an issue where the app's primary widget and the window manager's non-client-frame widget would fight over window titles.

A screenshot of the shelf is attached to the bug.

BUG=595850
TEST=launch mash, run mojo:task_viewer, note QuickLaunch shelf icon is default but TaskViewer icon is a gear

Review URL: https://codereview.chromium.org/1824183002

Cr-Commit-Position: refs/heads/master@{#383312}

1 files changed, 8 insertions, 0 deletions

diff --git a/mash/wm/non_client_frame_controller.cc b/mash/wm/non_client_frame_controller.cc
index ed6ad3a..774329a 100644
--- a/mash/wm/non_client_frame_controller.cc
+++ b/mash/wm/non_client_frame_controller.cc
@@ -125,6 +125,14 @@ class WmNativeWidgetMus : public views::NativeWidgetMus {
   void CenterWindow(const gfx::Size& size) override {
     // Do nothing. The client controls the size, not us.
   }
+  bool SetWindowTitle(const base::string16& title) override {
+    // Do nothing. The client controls the window title, not us.
+    return false;
+  }
+  void SetWindowIcons(const gfx::ImageSkia& window_icon,
+                      const gfx::ImageSkia& app_icon) override {
+    // Do nothing. The client controls window icons, not us.
+  }
   void UpdateClientArea() override {
     // This pushes the client area to the WS. We don't want to do that as
     // the client area should come from the client, not us.