Support creation of toplevel mus::Windows on separate displays

ash/mus/test/wm_test_base.cc

Index: ash/mus/test/wm_test_base.cc
diff --git a/ash/mus/test/wm_test_base.cc b/ash/mus/test/wm_test_base.cc
index c45eb6e73457fd27f8e573754940c7f90f90f533..5f7008870bbf9dd3ae2f106906029aace5f275ee 100644
--- a/ash/mus/test/wm_test_base.cc
+++ b/ash/mus/test/wm_test_base.cc
@@ -94,6 +94,19 @@ display::Display WmTestBase::GetSecondaryDisplay() {
   return roots.size() < 2 ? display::Display() : roots[1]->display();
 }
 
+RootWindowController* WmTestBase::GetPrimaryRootWindowController() {
+  std::vector<RootWindowController*> roots =
+      test_helper_->GetRootsOrderedByDisplayId();
+  DCHECK(!roots.empty());
+  return roots[0];
+}
+
+RootWindowController* WmTestBase::GetSecondaryRootWindowController() {
+  std::vector<RootWindowController*> roots =
+      test_helper_->GetRootsOrderedByDisplayId();
+  return roots.size() < 2 ? nullptr : roots[1];
+}
+
 ui::Window* WmTestBase::CreateTestWindow(const gfx::Rect& bounds) {
   return CreateTestWindow(bounds, ui::wm::WINDOW_TYPE_NORMAL);
 }
@@ -123,14 +136,22 @@ ui::Window* WmTestBase::CreateTestWindow(const gfx::Rect& bounds,
   return window;
 }
 
-ui::Window* WmTestBase::CreateFullscreenTestWindow() {
+ui::Window* WmTestBase::CreateFullscreenTestWindow(
+    RootWindowController* root = nullptr) {
   std::map<std::string, std::vector<uint8_t>> properties;
   properties[ui::mojom::WindowManager::kShowState_Property] =
       mojo::ConvertTo<std::vector<uint8_t>>(
           static_cast<int32_t>(ui::mojom::ShowState::FULLSCREEN));
-  ui::Window* window = test_helper_->GetRootsOrderedByDisplayId()[0]
-                           ->window_manager()
-                           ->NewTopLevelWindow(&properties);
+
+  ui::Window* window = nullptr;
+  if (root) {
+    properties[ui::mojom::WindowManager::kInitialDisplayId_Property] =
+        mojo::ConvertTo<std::vector<uint8_t>>(root->display().id());
+    window = root->window_manager()->NewTopLevelWindow(&properties);

[mfomitchev, 2016/11/18 20:35:58]

I think window manager is the same for all root windows? If so we don't actually
need RootWindowController here as an arg to this function. What we need is the
display id. So maybe this function could take display id (or at least Display)
instead of RWC pointer. And then we can also get rid of the new
GetPrimary/SecondaryRootWindowController methods.

(You could still keep CreateFullscreenTestWindow() with no args if you wish, it
should just call CreateFullscreenTestWindow(<id of the first display>) so that
there's no code duplication.

[thanhph, 2016/11/18 20:53:08]

Great stuff here Mikhail, thanks! The WM is the same for all root windows. I
have refactored/reduce the code to your suggestion. Thanks! 

+  } else
+    window = test_helper_->GetRootsOrderedByDisplayId()[0]
+                 ->window_manager()
+                 ->NewTopLevelWindow(&properties);
   window->SetVisible(true);
   return window;
 }