Ozone caca: Fix segfault during GPU initialization

ui/ozone/platform/caca/ozone_platform_caca.cc

 // Copyright 2014 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/ozone/platform/caca/ozone_platform_caca.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "ui/events/ozone/layout/keyboard_layout_engine_manager.h"
 #include "ui/events/ozone/layout/no/no_keyboard_layout_engine.h"
@@ skipping 55 matching lines @@
     overlay_manager_.reset(new StubOverlayManager());
     event_source_.reset(new CacaEventSource());
     cursor_factory_ozone_.reset(new CursorFactoryOzone());
     gpu_platform_support_host_.reset(CreateStubGpuPlatformSupportHost());
     input_controller_ = CreateStubInputController();
     KeyboardLayoutEngineManager::SetKeyboardLayoutEngine(
         base::MakeUnique<NoKeyboardLayoutEngine>());
   }
 
   void InitializeGPU() override {
+    if (!window_manager_) {
+      // The return value of GetSurfaceFactoryOzone() must be non-null so a
+      // dummy instance of CacaWindowManager is needed to make the GPU
+      // initialization gracefully fail.
+      window_manager_.reset(new CacaWindowManager);
+    }
   }
 
  private:
   std::unique_ptr<CacaWindowManager> window_manager_;
   std::unique_ptr<CacaEventSource> event_source_;
   std::unique_ptr<CursorFactoryOzone> cursor_factory_ozone_;
   std::unique_ptr<GpuPlatformSupportHost> gpu_platform_support_host_;
   std::unique_ptr<InputController> input_controller_;
   std::unique_ptr<OverlayManagerOzone> overlay_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(OzonePlatformCaca);
 };
 
 }  // namespace
 
 OzonePlatform* CreateOzonePlatformCaca() {
   return new OzonePlatformCaca;
 }
 
 }  // namespace ui