Allow Linux builds using Ozone to rely on default Create() methods.

Linux builds using Aura and Ozone (i.e. Chromecast) must be able to use
the non-x11 implementations of ui::AXPlatformNode::Create() and
ui::NativeViewAccessibility::Create(). Modify the gaurds around the
default implementations of these to account for this type of build.

BUG=

Review URL: https://codereview.chromium.org/1465453002

Cr-Commit-Position: refs/heads/master@{#360870}

ui/accessibility/platform/ax_platform_node.cc

@@ -9,12 +9,12 @@
 
 namespace ui {
 
-#if !defined(OS_MACOSX) && !defined(OS_WIN) && !(defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if !defined(PLATFORM_HAS_AX_PLATFORM_NODE_IMPL)
 // static
 AXPlatformNode* AXPlatformNode::Create(AXPlatformNodeDelegate* delegate) {
   return nullptr;
 }
-#endif
+#endif  // !defined(PLATFORM_HAS_AX_PLATFORM_NODE_IMPL)
 
 #if !defined(OS_WIN)
 // This is the default implementation for platforms where native views

ui/accessibility/platform/ax_platform_node.h

@@ -9,6 +9,22 @@
 #include "ui/accessibility/ax_export.h"
 #include "ui/gfx/native_widget_types.h"
 
+// Set PLATFORM_HAS_AX_PLATFORM_NODE_IMPL if this platform has a specific
+// implementation of AxPlatfromNode::Create().
+#undef PLATFORM_HAS_AX_PLATFORM_NODE_IMPL
+
+#if defined(OS_WIN)
+#define PLATFORM_HAS_AX_PLATFORM_NODE_IMPL 1
+#endif
+
+#if defined(OS_MACOSX)
+#define PLATFORM_HAS_AX_PLATFORM_NODE_IMPL 1
+#endif
+
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS) && defined(USE_X11)
+#define PLATFORM_HAS_AX_PLATFORM_NODE_IMPL 1
+#endif
+
 namespace ui {
 
 class AXPlatformNodeDelegate;

ui/views/accessibility/native_view_accessibility.cc

@@ -13,12 +13,12 @@
 
 namespace views {
 
-#if !defined(OS_WIN) && !(defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
 // static
 NativeViewAccessibility* NativeViewAccessibility::Create(View* view) {
   return new NativeViewAccessibility(view);
 }
-#endif
+#endif  // !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
 
 NativeViewAccessibility::NativeViewAccessibility(View* view)
     : view_(view),

ui/views/accessibility/native_view_accessibility.h

@@ -12,6 +12,18 @@
 #include "ui/views/views_export.h"
 #include "ui/views/widget/widget_observer.h"
 
+// Set PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL if this platform has a
+// specific implementation of NativeViewAccessibility::Create().
+#undef PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL
+
+#if defined(OS_WIN)
+#define PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL 1
+#endif
+
+#if defined(OS_LINUX) && defined(USE_X11) && !defined(OS_CHROMEOS)
+#define PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL 1
+#endif
+
 namespace views {
 
 class View;