[mus+ash] Fixes minimum browser window size (store / retrieve kPreferredSize property)

chrome/browser/ui/views/frame/browser_non_client_frame_view_mus.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/frame/browser_non_client_frame_view_mus.h"
 
 #include <algorithm>
 
 #include "chrome/browser/profiles/profiles_state.h"
 #include "chrome/browser/themes/theme_properties.h"
@@ skipping 318 matching lines @@
   int min_width = std::max(min_frame_width, min_client_view_size.width());
   if (browser_view()->IsTabStripVisible()) {
     // Ensure that the minimum width is enough to hold a minimum width tab strip
     // at its usual insets.
     int min_tabstrip_width =
         browser_view()->tabstrip()->GetMinimumSize().width();
     min_width =
         std::max(min_width, min_tabstrip_width + GetTabStripLeftInset() +
                                 GetTabStripRightInset());
   }
-  return gfx::Size(min_width, min_client_view_size.height());
+  gfx::Size min_size(min_width, min_client_view_size.height());
+
+  aura::Window* frame_window = frame()->GetNativeWindow();
+  const gfx::Size* min_window_size =
+      frame_window->GetProperty(aura::client::kMinimumSize);
+  if (!min_window_size || *min_window_size != min_size) {
+    frame_window->SetProperty(aura::client::kMinimumSize,
+                              new gfx::Size(min_size));
+  }
+  return min_size;

[sadrul, 2017/06/01 17:14:20]

This is the only part that I am a bit worried about. Specifically, this
information in ash can be stale.

The information the minimum-size seems to depend on are:
 a. Minimum size of the client_view.
 b. frame_values().
 c. tab-strip visibility.
 d. Minimum width of tabstrip.
 e. left-inset of the tabstrip.
 f. right-inset of the tabstrip.

I think b, c, d, e never change after BrowserNonClientFrameViewMus has been
initialized.

f depends on the profile-switcher icon, but I believe we do not use that
chromeos. So f should also never change after BNCFVMus has been initialized.

So the remaining unknown is (a). I guess the client_view is a BrowserView? Looks
like its minimum size is determined by BrowserViewLayout, which takes the
minimum-size of the following views to determine the minimum-size of the
client_view:
 1. tab-strip.
 2. toolbar.
 3. bookmark bar.
 4. infobar.

Hm ... this is already getting too complex.

Essentially, what I think should happen is that the minimum-size should be set
during/right after BNCFVMus is initialized, and then any time something it
depends on changes. Maybe BrowserView can notify back when anything in 1-4
change?

[varkha, 2017/06/19 15:57:36]

Thanks for the ideas. Did you have something like this wiring in mind?

 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // TabIconViewModel:
 
 bool BrowserNonClientFrameViewMus::ShouldTabIconViewAnimate() const {
   // This function is queried during the creation of the window as the
   // TabIconView we host is initialized, so we need to null check the selected
   // WebContents because in this condition there is not yet a selected tab.
   content::WebContents* current_tab = browser_view()->GetActiveWebContents();
@@ skipping 166 matching lines @@
   // TODO: move ash_layout_constants to ash/public/cpp.
   const bool restored = !frame()->IsMaximized() && !frame()->IsFullscreen();
   return GetAshLayoutSize(restored
                               ? AshLayoutSize::BROWSER_RESTORED_CAPTION_BUTTON
                               : AshLayoutSize::BROWSER_MAXIMIZED_CAPTION_BUTTON)
       .height();
 #else
   return views::WindowManagerFrameValues::instance().normal_insets.top();
 #endif
 }