ozone: gpu: Add plumbing for platform-specific gpu messaging

ui/ozone/platform/caca/ozone_platform_caca.cc

Index: ui/ozone/platform/caca/ozone_platform_caca.cc
diff --git a/ui/ozone/platform/caca/ozone_platform_caca.cc b/ui/ozone/platform/caca/ozone_platform_caca.cc
index a74379b58ca5fbc91c17b1cc3fb9f731f5455100..b34f5ca92d19d5fd4092adaf6a0cb794010b1d7d 100644
--- a/ui/ozone/platform/caca/ozone_platform_caca.cc
+++ b/ui/ozone/platform/caca/ozone_platform_caca.cc
@@ -34,6 +34,12 @@ class OzonePlatformCaca : public OzonePlatform {
   virtual CursorFactoryOzone* GetCursorFactoryOzone() OVERRIDE {
     return cursor_factory_ozone_.get();
   }
+  virtual GpuPlatformSupport* GetGpuPlatformSupport() OVERRIDE {
+    return NULL;  // no GPU support
+  }
+  virtual GpuPlatformSupportHost* GetGpuPlatformSupportHost() OVERRIDE {
+    return NULL;  // no GPU support
+  }
 
 #if defined(OS_CHROMEOS)
   virtual scoped_ptr<NativeDisplayDelegate> CreateNativeDisplayDelegate()