From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: msizanoen1 <msizanoen@qtmlabs.xyz>
Date: Tue, 19 Jul 2022 05:11:06 +0200
Subject: Add maximized parameter to LinuxUI::GetWindowFrameProvider

This allows ClientFrameViewLinux to instruct the toolkit to draw the window
decorations in maximized mode where needed, preventing empty space caused
by decoration shadows and rounded titlebars around the window while maximized.

diff --git a/ui/gtk/gtk_ui.cc b/ui/gtk/gtk_ui.cc
index 12193ad9090de969b81fa6aa6bed9520aea5bae1..99ea60219b39a6864bdea45ba0917316bff7f2d9 100644
--- a/ui/gtk/gtk_ui.cc
+++ b/ui/gtk/gtk_ui.cc
@@ -556,13 +556,15 @@ std::unique_ptr<views::NavButtonProvider> GtkUi::CreateNavButtonProvider() {
   return nullptr;
 }
 
-views::WindowFrameProvider* GtkUi::GetWindowFrameProvider(bool solid_frame) {
+views::WindowFrameProvider* GtkUi::GetWindowFrameProvider(bool solid_frame, bool maximized) {
   if (!GtkCheckVersion(3, 14))
     return nullptr;
   auto& provider =
-      solid_frame ? solid_frame_provider_ : transparent_frame_provider_;
+      maximized
+        ? (solid_frame ? solid_maximized_frame_provider_ : transparent_maximized_frame_provider_)
+        : (solid_frame ? solid_frame_provider_ : transparent_frame_provider_);
   if (!provider)
-    provider = std::make_unique<gtk::WindowFrameProviderGtk>(solid_frame);
+    provider = std::make_unique<gtk::WindowFrameProviderGtk>(solid_frame, maximized);
   return provider.get();
 }
 
diff --git a/ui/gtk/gtk_ui.h b/ui/gtk/gtk_ui.h
index 65f9d6c81804d1b0efb88ced4a9c80c000ba0f5a..35d851a054a2b2f9887c77a9faaf16ce1aa363b9 100644
--- a/ui/gtk/gtk_ui.h
+++ b/ui/gtk/gtk_ui.h
@@ -89,7 +89,7 @@ class GtkUi : public views::LinuxUI {
   bool PreferDarkTheme() const override;
   bool AnimationsEnabled() const override;
   std::unique_ptr<views::NavButtonProvider> CreateNavButtonProvider() override;
-  views::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) override;
+  views::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame, bool maximized) override;
   base::flat_map<std::string, std::string> GetKeyboardLayoutMap() override;
   std::string GetCursorThemeName() override;
   int GetCursorThemeSize() override;
@@ -188,6 +188,8 @@ class GtkUi : public views::LinuxUI {
   // while Chrome is running.
   std::unique_ptr<views::WindowFrameProvider> solid_frame_provider_;
   std::unique_ptr<views::WindowFrameProvider> transparent_frame_provider_;
+  std::unique_ptr<views::WindowFrameProvider> solid_maximized_frame_provider_;
+  std::unique_ptr<views::WindowFrameProvider> transparent_maximized_frame_provider_;
 };
 
 }  // namespace gtk
diff --git a/ui/gtk/window_frame_provider_gtk.cc b/ui/gtk/window_frame_provider_gtk.cc
index e4dbdad327eb77994ffd7f068c67336a19897915..d3ae0636455489a7c7443df85cb769952c98aca2 100644
--- a/ui/gtk/window_frame_provider_gtk.cc
+++ b/ui/gtk/window_frame_provider_gtk.cc
@@ -38,16 +38,18 @@ std::string GetThemeName() {
   return theme_string;
 }
 
-GtkCssContext WindowContext(bool solid_frame, bool focused) {
+GtkCssContext WindowContext(bool solid_frame, bool maximized, bool focused) {
   std::string selector = "#window.background.";
   selector += solid_frame ? "solid-csd" : "csd";
+  if (maximized)
+    selector += ".maximized";
   if (!focused)
     selector += ":inactive";
   return AppendCssNodeToStyleContext({}, selector);
 }
 
-GtkCssContext DecorationContext(bool solid_frame, bool focused) {
-  auto context = WindowContext(solid_frame, focused);
+GtkCssContext DecorationContext(bool solid_frame, bool maximized, bool focused) {
+  auto context = WindowContext(solid_frame, maximized, focused);
   // GTK4 renders the decoration directly on the window.
   if (!GtkCheckVersion(4))
     context = AppendCssNodeToStyleContext(context, "#decoration");
@@ -64,8 +66,8 @@ GtkCssContext DecorationContext(bool solid_frame, bool focused) {
   return context;
 }
 
-GtkCssContext HeaderContext(bool solid_frame, bool focused) {
-  auto context = WindowContext(solid_frame, focused);
+GtkCssContext HeaderContext(bool solid_frame, bool maximized, bool focused) {
+  auto context = WindowContext(solid_frame, maximized, focused);
   context =
       AppendCssNodeToStyleContext(context, "#headerbar.header-bar.titlebar");
   if (!focused)
@@ -110,8 +112,8 @@ int ComputeTopCornerRadius() {
   // need to experimentally determine the corner radius by rendering a sample.
   // Additionally, in GTK4, the headerbar corners get clipped by the window
   // rather than the headerbar having its own rounded corners.
-  auto context = GtkCheckVersion(4) ? DecorationContext(false, false)
-                                    : HeaderContext(false, false);
+  auto context = GtkCheckVersion(4) ? DecorationContext(false, false, false)
+                                    : HeaderContext(false, false, false);
   ApplyCssToContext(context, R"(window, headerbar {
     background-image: none;
     background-color: black;
@@ -169,8 +171,8 @@ void WindowFrameProviderGtk::Asset::CloneFrom(
   unfocused_bitmap = src.unfocused_bitmap;
 }
 
-WindowFrameProviderGtk::WindowFrameProviderGtk(bool solid_frame)
-    : solid_frame_(solid_frame) {}
+WindowFrameProviderGtk::WindowFrameProviderGtk(bool solid_frame, bool maximized)
+    : solid_frame_(solid_frame), maximized_(maximized) {}
 
 WindowFrameProviderGtk::~WindowFrameProviderGtk() = default;
 
@@ -264,7 +266,7 @@ void WindowFrameProviderGtk::PaintWindowFrame(gfx::Canvas* canvas,
       top_area_height_dip * scale - asset.frame_thickness_px.top();
 
   auto header = PaintHeaderbar({client_bounds_px.width(), top_area_height_px},
-                               HeaderContext(solid_frame_, focused), scale);
+                               HeaderContext(solid_frame_, maximized_, focused), scale);
   image = gfx::ImageSkia::CreateFrom1xBitmap(header);
   // In GTK4, the headerbar gets clipped by the window.
   if (GtkCheckVersion(4)) {
@@ -296,7 +298,7 @@ void WindowFrameProviderGtk::MaybeUpdateBitmaps(float scale) {
 
   gfx::Rect frame_bounds_dip(kMaxFrameSizeDip, kMaxFrameSizeDip,
                              2 * kMaxFrameSizeDip, 2 * kMaxFrameSizeDip);
-  auto focused_context = DecorationContext(solid_frame_, true);
+  auto focused_context = DecorationContext(solid_frame_, maximized_, true);
   frame_bounds_dip.Inset(-GtkStyleContextGetPadding(focused_context));
   frame_bounds_dip.Inset(-GtkStyleContextGetBorder(focused_context));
   gfx::Size bitmap_size(BitmapSizePx(asset), BitmapSizePx(asset));
@@ -304,7 +306,7 @@ void WindowFrameProviderGtk::MaybeUpdateBitmaps(float scale) {
       PaintBitmap(bitmap_size, frame_bounds_dip, focused_context, scale);
   asset.unfocused_bitmap =
       PaintBitmap(bitmap_size, frame_bounds_dip,
-                  DecorationContext(solid_frame_, false), scale);
+                  DecorationContext(solid_frame_, maximized_, false), scale);
 
   // In GTK4, there's no way to obtain the frame thickness from CSS values
   // directly, so we must determine it experimentally based on the drawn
diff --git a/ui/gtk/window_frame_provider_gtk.h b/ui/gtk/window_frame_provider_gtk.h
index d3039d73161378197557947aece88d2710c1e486..f7d4605938210b0b75517bb7bcab28b588a16520 100644
--- a/ui/gtk/window_frame_provider_gtk.h
+++ b/ui/gtk/window_frame_provider_gtk.h
@@ -14,7 +14,7 @@ namespace gtk {
 
 class WindowFrameProviderGtk : public views::WindowFrameProvider {
  public:
-  explicit WindowFrameProviderGtk(bool solid_frame);
+  explicit WindowFrameProviderGtk(bool solid_frame, bool maximized);
 
   WindowFrameProviderGtk(const WindowFrameProviderGtk&) = delete;
   WindowFrameProviderGtk& operator=(const WindowFrameProviderGtk&) = delete;
@@ -69,6 +69,9 @@ class WindowFrameProviderGtk : public views::WindowFrameProvider {
 
   // Cached bitmaps and metrics.  The scale is rounded to percent.
   base::flat_map<int, Asset> assets_;
+
+  // Whether to draw the window decorations as maximized.
+  bool maximized_;
 };
 
 }  // namespace gtk
diff --git a/ui/views/linux_ui/linux_ui.h b/ui/views/linux_ui/linux_ui.h
index 7d59a2c9ff87cf9d8cb3ed0b45e34e2831545d28..a6ae4feec8df8f149a9ebbe1c3d2252db73135db 100644
--- a/ui/views/linux_ui/linux_ui.h
+++ b/ui/views/linux_ui/linux_ui.h
@@ -170,7 +170,7 @@ class VIEWS_EXPORT LinuxUI : public ui::LinuxInputMethodContextFactory,
   // if transparency is unsupported and the frame should be rendered opaque.
   // The returned object is not owned by the caller and will remain alive until
   // the process ends.
-  virtual WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) = 0;
+  virtual WindowFrameProvider* GetWindowFrameProvider(bool solid_frame, bool maximized) = 0;
 
   // Returns a map of KeyboardEvent code to KeyboardEvent key values.
   virtual base::flat_map<std::string, std::string> GetKeyboardLayoutMap() = 0;
