chrome: Add support for Alloy style browsers and windows (see #3681)

Split the Alloy runtime into bootstrap and style components. Support
creation of Alloy style browsers and windows with the Chrome runtime.
Chrome runtime (`--enable-chrome-runtime`) + Alloy style
(`--use-alloy-style`) supports Views (`--use-views`), native parent
(`--use-native`) and windowless rendering
(`--off-screen-rendering-enabled`).

Print preview is supported in all cases except with windowless rendering
on all platforms and native parent on MacOS. It is disabled by default
with Alloy style for legacy compatibility. Where supported it can be
enabled or disabled globally using `--[enable|disable]-print-preview` or
configured on a per-RequestContext basis using the
`printing.print_preview_disabled` preference. It also behaves as
expected when triggered via the PDF viewer print button.

Chrome runtime + Alloy style behavior differs from Alloy runtime in the
following significant ways:

- Supports Chrome error pages by default.
- DevTools popups are Chrome style only (cannot be windowless).
- The Alloy extension API will not supported.

Chrome runtime + Alloy style passes all expected Alloy ceftests except
the following:

- `DisplayTest.AutoResize` (Alloy extension API not supported)
- `DownloadTest.*` (Download API not yet supported)
- `ExtensionTest.*` (Alloy extension API not supported)

This change also adds Chrome runtime support for
CefContextMenuHandler::RunContextMenu (see #3293).

This change also explicitly blocks (and doesn't retry) FrameAttached
requests from PDF viewer and print preview excluded frames (see #3664).

Known issues specific to Chrome runtime + Alloy style:
- DevTools popup with windowless rendering doesn't load successfully.
  Use windowed rendering or remote debugging as a workaround.
- Chrome style Window with Alloy style BrowserView (`--use-alloy-style
  --use-chrome-style-window`) does not show Chrome theme changes.

To test:
- Run `ceftests --enable-chrome-runtime --use-alloy-style
       [--use-chrome-style-window] [--use-views|--use-native]
       --gtest_filter=...`
- Run `cefclient --enable-chrome-runtime --use-alloy-style
       [--use-chrome-style-window]
       [--use-views|--use-native|--off-screen-rendering-enabled]`
- Run `cefsimple --enable-chrome-runtime --use-alloy-style [--use-views]`

libcef/browser/chrome/views/chrome_child_window.cc

@@ -8,6 +8,8 @@
 #include "libcef/browser/views/browser_view_impl.h"
 #include "libcef/browser/views/window_impl.h"
 
+#include "ui/gfx/native_widget_types.h"
+
 #if BUILDFLAG(IS_WIN)
 #include "libcef/browser/native/browser_platform_delegate_native_win.h"
 #include "ui/views/win/hwnd_util.h"
@@ -15,6 +17,23 @@
 
 namespace {
 
+gfx::AcceleratedWidget GetParentWidget(const CefWindowInfo& window_info) {
+#if !BUILDFLAG(IS_MAC)
+  return window_info.parent_window;
+#else
+  // Chrome style is not supported with native parent on MacOS. See issue #3294.
+  return gfx::kNullAcceleratedWidget;
+#endif
+}
+
+CefWindowHandle GetParentHandle(const CefWindowInfo& window_info) {
+#if !BUILDFLAG(IS_MAC)
+  return window_info.parent_window;
+#else
+  return window_info.parent_view;
+#endif
+}
+
 class ChildWindowDelegate : public CefWindowDelegate {
  public:
   ChildWindowDelegate(const ChildWindowDelegate&) = delete;
@@ -61,8 +80,7 @@ class ChildWindowDelegate : public CefWindowDelegate {
     DCHECK(widget_hwnd);
 
     // The native delegate needs state to perform some actions.
-    auto browser =
-        static_cast<CefBrowserHostBase*>(browser_view_->GetBrowser().get());
+    auto browser = CefBrowserHostBase::FromBrowser(browser_view_->GetBrowser());
     auto platform_delegate = browser->platform_delegate();
     DCHECK(platform_delegate->IsViewsHosted());
     auto chrome_delegate =
@@ -115,6 +133,8 @@ class ChildBrowserViewDelegate : public CefBrowserViewDelegate {
   ChildBrowserViewDelegate(const ChildBrowserViewDelegate&) = delete;
   ChildBrowserViewDelegate& operator=(const ChildBrowserViewDelegate&) = delete;
 
+  // |browser_view| will be nullptr when called for popups with non-Views-hosted
+  // opener.
   CefRefPtr<CefBrowserViewDelegate> GetDelegateForPopupBrowserView(
       CefRefPtr<CefBrowserView> browser_view,
       const CefBrowserSettings& settings,
@@ -123,11 +143,13 @@ class ChildBrowserViewDelegate : public CefBrowserViewDelegate {
     return new ChildBrowserViewDelegate();
   }
 
+  // |browser_view| will be nullptr when called for popups with non-Views-hosted
+  // opener.
   bool OnPopupBrowserViewCreated(CefRefPtr<CefBrowserView> browser_view,
                                  CefRefPtr<CefBrowserView> popup_browser_view,
                                  bool is_devtools) override {
-    auto new_browser = static_cast<CefBrowserHostBase*>(
-        popup_browser_view->GetBrowser().get());
+    auto new_browser =
+        CefBrowserHostBase::FromBrowser(popup_browser_view->GetBrowser());
     auto new_platform_delegate = new_browser->platform_delegate();
     DCHECK(new_platform_delegate->IsViewsHosted());
     auto new_platform_delegate_impl =
@@ -136,8 +158,7 @@ class ChildBrowserViewDelegate : public CefBrowserViewDelegate {
 
     const auto& window_info =
         new_platform_delegate_impl->native_delegate()->window_info();
-    const auto parent_handle =
-        chrome_child_window::GetParentHandle(window_info);
+    const auto parent_handle = GetParentWidget(window_info);
     if (parent_handle != gfx::kNullAcceleratedWidget) {
       ChildWindowDelegate::Create(popup_browser_view, window_info,
                                   parent_handle);
@@ -158,15 +179,7 @@ class ChildBrowserViewDelegate : public CefBrowserViewDelegate {
 namespace chrome_child_window {
 
 bool HasParentHandle(const CefWindowInfo& window_info) {
-  return GetParentHandle(window_info) != gfx::kNullAcceleratedWidget;
-}
-
-gfx::AcceleratedWidget GetParentHandle(const CefWindowInfo& window_info) {
-#if !BUILDFLAG(IS_MAC)
-  return window_info.parent_window;
-#else
-  return gfx::kNullAcceleratedWidget;
-#endif
+  return GetParentHandle(window_info) != kNullWindowHandle;
 }
 
 CefRefPtr<CefBrowserHostBase> MaybeCreateChildBrowser(
@@ -181,7 +194,7 @@ CefRefPtr<CefBrowserHostBase> MaybeCreateChildBrowser(
     return nullptr;
   }
 
-  const auto parent_handle = GetParentHandle(*create_params.window_info);
+  const auto parent_handle = GetParentWidget(*create_params.window_info);
   if (parent_handle == gfx::kNullAcceleratedWidget) {
     return nullptr;
   }
@@ -195,7 +208,12 @@ CefRefPtr<CefBrowserHostBase> MaybeCreateChildBrowser(
   ChildWindowDelegate::Create(browser_view, *create_params.window_info,
                               parent_handle);
 
-  return static_cast<CefBrowserHostBase*>(browser_view->GetBrowser().get());
+  return CefBrowserHostBase::FromBrowser(browser_view->GetBrowser());
+}
+
+CefRefPtr<CefBrowserViewDelegate>
+GetDefaultBrowserViewDelegateForPopupOpener() {
+  return new ChildBrowserViewDelegate();
 }
 
 }  // namespace chrome_child_window