Don't build separate webview_chromium library

Just include wxWebViewChromium in the webview library if it's enabled
during the build.

There doesn't seem to be any reason to build a separate library for it,
it's not really different from the other disabled by default wxWebView
backend (Edge).

And now that we don't need to link with an extra library, there is also
no need to have a separate webview_chromium sample, so just add a
possibility to run webview sample itself using Chromium backend by
setting WX_WEBVIEW_BACKEND environment variable.

interface/wx/webview_chromium.h

@@ -31,37 +31,57 @@
 
     __General__
 
-    The wxWebViewChromium backend is built into a separate webview_chromium
-    library which depends on the webview library.
+    When wxWebViewChromium backend is enabled, it is compiled as part of the
+    webview library which means that this library depends on CEF and all
+    applications using it must be linked with it.
 
-    When building with CMake enable wxUSE_WEBVIEW_CHROMIUM and CEF can be
-    automatically downloaded during configuration based on your platform.
-    You can also download it manually from the CEF official binaries site at
-    https://cef-builds.spotifycdn.com/index.html and then build only
-    `libcef_dll_wrapper` -- but not the `libcef` itself.
+    Currently building wxWebViewChromium is possible only with configure-based
+    build system under Unix (including macOS) and using the provided MSVS
+    project files under MSW. Notably building it using CMake does not work.
 
-    For other build systems please follow the following instructions:
+    Before enabling wxWebViewChromium you need to ensure that CEF is available:
 
-    Once you have a copy of CEF, either from compiling it yourself or using
-    prebuilt binaries, you should copy it into `wx_root/3rdparty/cef`. To run the
-    webview_chromium sample you need to copy the CEF resources into the
-    sample directory. The following files need to be copied:
+    1. Download the binaries for your platform from the CEF official site at
+    https://cef-builds.spotifycdn.com/index.html ("Minimal Distribution" is
+    sufficient)
+    2. Unpack the archive into `3rdparty/cef` directory under wxWidgets source
+    directory.
+    3. Build `libcef_dll_wrapper` using the instructions provided in the CEF
+    distribution, but, in short, just by using `cmake` to do it.
+    4. Copy the static library binary in the platform-dependent location:
+      - Under MSW, copy `libcefl_dll_wrapper.lib` file to either
+      `3rdparty/cef/Release` or `3rdparty/cef/Debug` depending on the build
+      configuration (it's recommended to build CEF wrapper in both
+      configurations and so copy the two files to both locations).
+      - Under Unix (including macOS), copy `libcef_dll_wrapper.a` file to
+      `3rdparty/cef/libcef_dll_wrapper` directory.
 
-    - All files from either `wx_root/3rdparty/cef/Debug` or
-      `wx_root/3rdparty/cef/Release` folder, depending on your build type
+    Then enable wxWebViewChromium support:
+
+    - Under MSW, set `wxUSE_WEBVIEW_CHROMIUM` to 1 in `wx/msw/setup.h`.
+    - Under Unix, add `--enable-webviewchromium` option to configure command
+    line.
+
+    Finally, build wxWidgets as usual: the resulting webview library will
+    include wxWebViewChromium.
+
+    It is recommended to build webview sample to check that everything is
+    working as expected. Under Unix, the required CEF files will be copied to
+    the sample directory as part of the build process, but under MSW you need
+    to copy them manually before running the sample: please copy
+
+    - All files from either `3rdparty/cef/Debug` or
+      `3rdparty/cef/Release` folder, depending on your build type
     - The contents of the wx_root/3rdparty/cef/Resources folder.
 
+    to the directory containing `webview` executable.
+
     Please see CEF `README.txt` for more details and also note that when
     redistributing CEF you must abide by the terms of its `LICENSE.txt`.
 
-    When building wxWidgets you need to ensure wxWebViewChromium is enabled,
-    either by passing --enable-webviewchromium for autoconf based builds or
-    setting wxUSE_WEBVIEW_CHROMIUM equal to 1 in setup.h for Visual Studio
-    based builds.
-
-    When running applications using wxWebViewChromium, the command line option
-    `--type=xxx` is interpreted specially as it is used by CEF to launch helper
-    applications, so your program must not use this option for anything else.
+    Note that by default the webview sample uses the default platform-dependent
+    wxWebView backend and to use Chromium backend in it you need to set
+    `WX_WEBVIEW_BACKEND` environment variable to the value `wxWebViewChromium`.
 
 
     __Microsoft Windows Platform__
@@ -72,6 +92,9 @@
 
     Microsoft Visual C++ 2022 must be used to build wxWebViewChromium.
 
+    When linking an application using it, both `libcef.lib` and
+    `libcef_dll_wrapper.lib` should be included in the libraries list.
+
     __Linux with GTK__
 
     wxWebviewChromium currently only supports X11 and not Wayland, i.e. you
@@ -101,9 +124,9 @@
     etc) are required.
 
     For applications using wxWebviewChromium, below are the steps to make
-    it work, based off the webview_chromium sample bakefile.
+    it work, based off the webview sample bakefile.
 
-    1. Build the webview_chromium library.
+    1. Build the webview library with CEF support.
     2. Compile/link/package the `YourApp helper` app:
        - Require `cef_process_helper.cpp`
        - Require link frameworks: Chromium Embedded Framework.framework,
@@ -122,31 +145,31 @@
     Below is the wxWebviewChromium sample app bundle directory structure,
     omitting some resource files
 
-        webview_chromium.app
+        webview.app
         |____Contents
           |____MacOS
-          | |____webview_chromium
+          | |____webview
           |____Resources
           | |____wxmac.icns
           |____Frameworks
-          | |____webview_chromium Helper.app
+          | |____webview Helper.app
           | | |____Contents
           | |   |____MacOS
-          | |   | |____webview_chromium Helper
+          | |   | |____webview Helper
           | |   |____Resources
           | |   | |____wxmac.icns
           | |   |____Info.plist
-          | |____webview_chromium Helper (GPU).app
+          | |____webview Helper (GPU).app
           | | |____Contents
           | |   |____MacOS
-          | |   | |____webview_chromium Helper (GPU)
+          | |   | |____webview Helper (GPU)
           | |   |____Resources
           | |   | |____wxmac.icns
           | |   |____Info.plist
-          | |____webview_chromium Helper (Plugin).app
+          | |____webview Helper (Plugin).app
           | | |____Contents
           | |   |____MacOS
-          | |   | |____webview_chromium Helper (Plugin)
+          | |   | |____webview Helper (Plugin)
           | |   |____Resources
           | |   | |____wxmac.icns
           | |   |____Info.plist
@@ -166,23 +189,31 @@
           | | | |____libvk_swiftshader.dylib
           | | | |____libGLESv2.dylib
           | | |____Chromium Embedded Framework
-          | |____webview_chromium Helper (Renderer).app
+          | |____webview Helper (Renderer).app
           | | |____Contents
           | |   |____MacOS
-          | |   | |____webview_chromium Helper (Renderer)
+          | |   | |____webview Helper (Renderer)
           | |   |____Resources
           | |   | |____wxmac.icns
           | |   |____Info.plist
-          | |____webview_chromium Helper (Alerts).app
+          | |____webview Helper (Alerts).app
           |   |____Contents
           |     |____MacOS
-          |     | |____webview_chromium Helper (Alerts)
+          |     | |____webview Helper (Alerts)
           |     |____Resources
           |     | |____wxmac.icns
           |     |____Info.plist
           |____Info.plist
 
 
+    __Miscellaneous Notes__
+
+    When running applications using wxWebViewChromium, the command line option
+    `--type=xxx` is interpreted specially as it is used by CEF to launch helper
+    applications, so your program must not use this option for anything else.
+
+
+
     @section differences API Differences
 
     wxWebViewChromium aims to support the full wxWebView API, but there are
@@ -197,7 +228,7 @@
       if the @a output parameter is non-null, the function will always return false.
 
     @since 3.3.0
-    @library{wxwebview_chromium}
+    @library{wxwebview}
     @category{webview}
 
 **/