X11 and Ozone: fix use_x11 && use_x11 build for clipboard

When use_x11 && use_ozone are set to true at the same
time, the compiler throws an error about multiple definitions
of the Create() method for Clipboard.

Thus, to fix that, create a separate source file for
is_linux case that will choose what Clipboard impl to
use based on the IsUsingOzonePlatform feature flag.

Please note that this is a temp solution and it will
be removed once use_x11 goes away.

Please note that it's impossible to build use_x11 && use_ozone without
some hacks in PlatformCursor code. The changes to that are on their
way to upstream.

Bug: 1085700
Change-Id: I3a32b261ec01fd2a751127b5abda1147575b8e18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2247760
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779210}

ui/base/clipboard/BUILD.gn

@@ -115,13 +115,15 @@ jumbo_component("clipboard") {
   if (use_aura) {
     # Linux clipboard implementations.
     if (is_desktop_linux && !is_chromecast) {
+      sources += [ "clipboard_linux.cc" ]
       if (use_ozone) {
         sources += [
           "clipboard_ozone.cc",
           "clipboard_ozone.h",
         ]
         deps += [ "//ui/base" ]
-      } else if (use_x11) {
+      }
+      if (use_x11) {
         sources += [
           "clipboard_x11.cc",
           "clipboard_x11.h",

ui/base/clipboard/clipboard_linux.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/base/clipboard/clipboard.h"
+
+#if defined(USE_OZONE)
+#include "ui/base/clipboard/clipboard_ozone.h"
+#include "ui/base/ui_base_features.h"
+#endif
+
+#if defined(USE_X11)
+#include "ui/base/clipboard/clipboard_x11.h"
+#endif
+
+namespace ui {
+
+// Clipboard factory method.
+Clipboard* Clipboard::Create() {
+#if defined(USE_OZONE)
+  if (features::IsUsingOzonePlatform())
+    return new ClipboardOzone();
+#endif
+
+#if defined(USE_X11)
+  return new ClipboardX11();
+#else
+  NOTREACHED();
+  return nullptr;
+#endif
+}
+
+}  // namespace ui

ui/base/clipboard/clipboard_ozone.cc

@@ -15,6 +15,7 @@
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/timer/timer.h"
+#include "build/build_config.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/clipboard/clipboard_buffer.h"
 #include "ui/base/clipboard/clipboard_constants.h"
@@ -294,6 +295,8 @@ class ClipboardOzone::AsyncClipboardOzone {
   DISALLOW_COPY_AND_ASSIGN(AsyncClipboardOzone);
 };
 
+// Uses the factory in the clipboard_linux otherwise.
+#if defined(OS_CHROMEOS) || !defined(OS_LINUX)
 // Clipboard factory method.
 Clipboard* Clipboard::Create() {
 // linux-chromeos uses non-backed clipboard by default, but supports ozone x11
@@ -306,6 +309,7 @@ Clipboard* Clipboard::Create() {
 #endif
   return new ClipboardOzone;
 }
+#endif
 
 // ClipboardOzone implementation.
 ClipboardOzone::ClipboardOzone() {

ui/base/clipboard/clipboard_test_template.h

@@ -46,6 +46,7 @@
 #endif
 
 #if defined(USE_X11)
+#include "ui/base/ui_base_features.h"
 #include "ui/events/platform/platform_event_source.h"
 #endif
 
@@ -67,7 +68,8 @@ class ClipboardTest : public PlatformTest {
   void SetUp() override {
     PlatformTest::SetUp();
 #if defined(USE_X11)
-    event_source_ = ClipboardTraits::GetEventSource();
+    if (!features::IsUsingOzonePlatform())
+      event_source_ = ClipboardTraits::GetEventSource();
 #endif
     clipboard_ = ClipboardTraits::Create();
   }

ui/base/clipboard/clipboard_x11.cc

@@ -511,12 +511,6 @@ bool ClipboardX11::X11Details::DispatchXEvent(x11::Event* x11_event) {
   return false;
 }
 
-///////////////////////////////////////////////////////////////////////////////
-// Clipboard factory method.
-Clipboard* Clipboard::Create() {
-  return new ClipboardX11;
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 // ClipboardX11