[ios clean] Add overflow buttons for ToolsMenu.

ios/clean/chrome/browser/ui/toolbar/BUILD.gn

 # Copyright 2016 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.
 
 source_set("toolbar") {
   sources = [
     "toolbar_coordinator.h",
     "toolbar_coordinator.mm",
   ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
 
   deps = [
     ":toolbar_ui",
     "//base",
     "//ios/clean/chrome/browser",
     "//ios/clean/chrome/browser/ui/commands",
     "//ios/clean/chrome/browser/ui/tools",
     "//ios/shared/chrome/browser/coordinator_context",
     "//ios/web",
   ]
 }
 
 source_set("toolbar_ui") {
   sources = [
-    "toolbar_button+factory.h",
-    "toolbar_button+factory.mm",
-    "toolbar_button.h",
-    "toolbar_button.mm",
-    "toolbar_component_options.h",
     "toolbar_view_controller.h",
     "toolbar_view_controller.mm",
   ]
   deps = [
+    ":toolbar_components",
     "//base",
-    "//ios/chrome/app/theme",
-    "//ios/chrome/browser/ui",
     "//ios/clean/chrome/browser/ui/actions",
     "//ios/clean/chrome/browser/ui/animators",
     "//ios/clean/chrome/browser/ui/commands",
     "//ios/clean/chrome/browser/ui/tools",
   ]
   libs = [ "UIKit.framework" ]
   configs += [ "//build/config/compiler:enable_arc" ]
+}
+
+source_set("toolbar_components") {

[sczs, 2017/02/14 23:54:42]

This might or might not be end up being used by ToolsMenu once we're "done", but
I think its
still worth having good source_set modularity overall. Specially since we are
building this with the idea of replacing VC in the near future. 

[edchin, 2017/02/15 04:14:50]

The line between toolbar_ui and toolbar_components is not clear to me. For
example, a button is UI. 

[marq (ping after 24h), 2017/02/15 15:06:16]

I think the idea is that _components might be used by other _ui targets.

Another approach would be to move all of the button-specific stuff into
something like ui/buttons and have both toolbar and tools_menu depend on it.

[sczs, 2017/02/16 00:31:39]

Yes, that is the idea.
I guess I could rename this to toolbar_components_ui for now, that would make it
clear that this is UI ToolbarComponents related. If we end up reusing more
buttons later on we could move this to ui/buttons WDYT?

[edchin, 2017/02/16 01:21:00]

I'm okay with either, with a slight preference for ui/buttons if we think 
it will be used in more places than just toolbar. 

+  sources = [
+    "toolbar_button+factory.h",
+    "toolbar_button+factory.mm",
+    "toolbar_button.h",
+    "toolbar_button.mm",
+    "toolbar_component_options.h",
+  ]
+  deps = [
+    "//base",
+    "//ios/chrome/app/theme",
+    "//ios/chrome/browser/ui",
+  ]
+  libs = [ "UIKit.framework" ]
+  configs += [ "//build/config/compiler:enable_arc" ]
 }