Fix window/display bounds with multiple windows in mus.

services/ui/display/platform_screen_impl_ozone.cc

Index: services/ui/display/platform_screen_impl_ozone.cc
diff --git a/services/ui/display/platform_screen_impl_ozone.cc b/services/ui/display/platform_screen_impl_ozone.cc
index 9ab9d726325e82c8458d8f1395834ca55d671581..c4f1ada7c42de733cdd48d54424f1dc7f48f1bc0 100644
--- a/services/ui/display/platform_screen_impl_ozone.cc
+++ b/services/ui/display/platform_screen_impl_ozone.cc
@@ -4,6 +4,8 @@
 
 #include "services/ui/display/platform_screen_impl_ozone.h"
 
+#include <memory>
+
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/sys_info.h"
@@ -18,24 +20,6 @@
 namespace display {
 namespace {
 
-// TODO(rjkroege): Remove this code once ozone headless has the same
-// display creation semantics as ozone drm.
-// Some ozone platforms do not configure physical displays and so do not
-// callback into this class via the implementation of NativeDisplayObserver.
-// FixedSizeScreenConfiguration() short-circuits the implementation of display
-// configuration in this case by calling the |callback| provided to
-// ConfigurePhysicalDisplay() with a hard-coded |id| and |bounds|.
-void FixedSizeScreenConfiguration(
-    const PlatformScreen::ConfiguredDisplayCallback& callback) {
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch("multi-display")) {
-    // This really doesn't work properly. Use at your own risk.
-    callback.Run(100, gfx::Rect(800, 800));
-    callback.Run(200, gfx::Rect(800, 0, 800, 800));
-  } else {
-    callback.Run(100, gfx::Rect(0, 0, 1024, 768));
-  }
-}
-
 // Needed for DisplayConfigurator::ForceInitialConfigure.
 const SkColor kChromeOsBootColor = SkColorSetRGB(0xfe, 0xfe, 0xfe);
 
@@ -53,6 +37,9 @@ PlatformScreenImplOzone::~PlatformScreenImplOzone() {
 }
 
 void PlatformScreenImplOzone::Init() {
+  // We want display configuration to happen even off device to keep the control
+  // flow similar.
+  display_configurator_.set_configure_display(true);
   display_configurator_.AddObserver(this);
   display_configurator_.Init(
       ui::OzonePlatform::GetInstance()->CreateNativeDisplayDelegate(), false);
@@ -60,45 +47,65 @@ void PlatformScreenImplOzone::Init() {
 
 void PlatformScreenImplOzone::ConfigurePhysicalDisplay(
     const PlatformScreen::ConfiguredDisplayCallback& callback) {
+  callback_ = callback;
+
   if (base::SysInfo::IsRunningOnChromeOS()) {
-    callback_ = callback;
     display_configurator_.ForceInitialConfigure(kChromeOsBootColor);
   } else {
-    // PostTask()ed to maximize control flow similarity with the ChromeOS case.
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(&FixedSizeScreenConfiguration, callback));
+    if (base::CommandLine::ForCurrentProcess()->HasSwitch("multi-display")) {
+      // This really doesn't work properly. Use at your own risk.
+      display_configurator_.AddVirtualDisplay(gfx::Size(800, 800));
+      display_configurator_.AddVirtualDisplay(gfx::Size(800, 800));
+    } else {
+      display_configurator_.AddVirtualDisplay(gfx::Size(1024, 768));
+    }
   }
 }
 
+int64_t PlatformScreenImplOzone::GetPrimaryDisplayId() const {
+  return primary_display_id_;
+}
+
 void PlatformScreenImplOzone::OnDisplayModeChanged(
     const ui::DisplayConfigurator::DisplayStateList& displays) {
-  // TODO(kylechar): Remove check when adding/removing displays is supported.
-  CHECK(!callback_.is_null());
-
   if (displays.size() > 1) {
     LOG(ERROR)
         << "Mus doesn't really support multiple displays, expect it to crash";
   }
 
-  gfx::Point origin;
-  for (auto* display : displays) {
-    const ui::DisplayMode* current_mode = display->current_mode();
-    gfx::Rect bounds(origin, current_mode->size());
+  // TODO(kylechar): Use DisplayLayout/DisplayLayoutStore here when possible.
+  std::set<uint64_t> all_displays;
+  for (ui::DisplaySnapshot* display : displays) {
+    const int64_t id = display->display_id();
+
+    all_displays.insert(id);
+
+    if (displays_.find(id) != displays_.end())
+      continue;
 
-    callback_.Run(display->display_id(), bounds);
+    const ui::DisplayMode* current_mode = display->current_mode();
+    gfx::Rect bounds(next_display_origin_, current_mode->size());
 
     // Move the origin so that next display is to the right of current display.
-    origin.Offset(current_mode->size().width(), 0);
+    next_display_origin_.Offset(current_mode->size().width(), 0);
+
+    // The first display added will be our primary display.
+    if (displays_.empty())
+      primary_display_id_ = id;
+
+    // Keep track of what displays have already been added.
+    displays_.insert(display->display_id());
+
+    callback_.Run(id, bounds);
   }
 
-  callback_.Reset();
+  DCHECK(displays_ == all_displays) << "Removing displays is not supported.";
 }
 
 void PlatformScreenImplOzone::OnDisplayModeChangeFailed(
     const ui::DisplayConfigurator::DisplayStateList& displays,
     ui::MultipleDisplayState failed_new_state) {
   LOG(ERROR) << "OnDisplayModeChangeFailed from DisplayConfigurator";
-  callback_.Reset();
 }
 
 }  // namespace display