Prevent a window from being put into fullscreen upon startup on desktop Linux

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index ebbd90410c82818939a494bc89e5a802eaab9d76..fe3610d1c9efab9244adbfa1355f90053c075831 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -30,6 +30,7 @@
 #include "ui/events/x/device_data_manager_x11.h"
 #include "ui/events/x/device_list_cache_x.h"
 #include "ui/events/x/touch_factory_x11.h"
+#include "ui/gfx/display.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_skia_rep.h"
 #include "ui/gfx/insets.h"
@@ -385,7 +386,8 @@ bool DesktopWindowTreeHostX11::IsVisible() const {
   return window_mapped_;
 }
 
-void DesktopWindowTreeHostX11::SetSize(const gfx::Size& size) {
+void DesktopWindowTreeHostX11::SetSize(const gfx::Size& requested_size) {
+  gfx::Size size = AdjustSize(requested_size);
   bool size_changed = bounds_.size() != size;
   XResizeWindow(xdisplay_, xwindow_, size.width(), size.height());
   bounds_.set_size(size);
@@ -520,6 +522,20 @@ bool DesktopWindowTreeHostX11::IsActive() const {
 }
 
 void DesktopWindowTreeHostX11::Maximize() {
+  if (HasWMSpecProperty("_NET_WM_STATE_FULLSCREEN")) {

[pkotwicz, 2014/07/25 19:31:51]

It is possible for a user to still inadvertently put the window into fullscreen
by resizing it or by dragging the window header. The code here allows the user
to get out of fullscreen if they press the maximize button enough times.

+    // Unfullscreen the window if it is fullscreen.
+    SetWMSpecState(false,
+                   atom_cache_.GetAtom("_NET_WM_STATE_FULLSCREEN"),
+                   None);
+
+    // Resize the window so that it does not have the same size as a monitor.
+    // (Otherwise, some window managers immediately put the window back in
+    // fullscreen mode).
+    gfx::Rect adjusted_bounds(bounds_.origin(), AdjustSize(bounds_.size()));
+    if (adjusted_bounds != bounds_)
+      SetBounds(adjusted_bounds);
+  }
+
   // When we are in the process of requesting to maximize a window, we can
   // accurately keep track of our restored bounds instead of relying on the
   // heuristics that are in the PropertyNotify and ConfigureNotify handlers.
@@ -850,7 +866,9 @@ gfx::Rect DesktopWindowTreeHostX11::GetBounds() const {
   return bounds_;
 }
 
-void DesktopWindowTreeHostX11::SetBounds(const gfx::Rect& bounds) {
+void DesktopWindowTreeHostX11::SetBounds(const gfx::Rect& requested_bounds) {
+  gfx::Rect bounds(requested_bounds.origin(),
+                   AdjustSize(requested_bounds.size()));
   bool origin_changed = bounds_.origin() != bounds.origin();
   bool size_changed = bounds_.size() != bounds.size();
   XWindowChanges changes = {0};
@@ -1038,7 +1056,8 @@ void DesktopWindowTreeHostX11::InitX11Window(
     }
   }
 
-  bounds_ = params.bounds;
+  bounds_ = gfx::Rect(params.bounds.origin(),
+                      AdjustSize(params.bounds.size()));
   xwindow_ = XCreateWindow(
       xdisplay_, x_root_window_,
       bounds_.x(), bounds_.y(),
@@ -1171,6 +1190,21 @@ void DesktopWindowTreeHostX11::InitX11Window(
   CreateCompositor(GetAcceleratedWidget());
 }
 
+gfx::Size DesktopWindowTreeHostX11::AdjustSize(
+    const gfx::Size& requested_size) {
+  std::vector<gfx::Display> displays =
+      gfx::Screen::GetScreenByType(gfx::SCREEN_TYPE_NATIVE)->GetAllDisplays();
+  // Compare against all monitor sizes. The window manager can move the window
+  // to whichever monitor it wants.
+  for (size_t i = 0; i < displays.size(); ++i) {
+    if (requested_size == displays[i].size()) {
+      return gfx::Size(requested_size.width() - 1,
+                       requested_size.height() - 1);

[pkotwicz, 2014/07/25 19:31:51]

Ensuring that the window's non-maximized size does not match the screen's width
or height seems sufficient to prevent a window which is opened as maximized from
getting put into fullscreen when unmaximized.

+    }
+  }
+  return requested_size;
+}
+
 void DesktopWindowTreeHostX11::OnWMStateUpdated() {
   std::vector< ::Atom> atom_list;
   if (!ui::GetAtomArrayProperty(xwindow_, "_NET_WM_STATE", &atom_list))