Revert of Add OpenGL support to Linux viewer

tools/viewer/Viewer.cpp

Index: tools/viewer/Viewer.cpp
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index c1f890a4c3423df5606a1a8517b9dccab0800158..6519a3c8be59007e89ee882c6739638fa61a8291 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -41,7 +41,7 @@
     return viewer->onUIStateChanged(stateName, stateValue);
 }
 
-DEFINE_bool2(fullscreen, f, false, "Run fullscreen.");
+DEFINE_bool2(fullscreen, f, true, "Run fullscreen.");
 DEFINE_string(key, "", "Space-separated key/value pairs to add to JSON identifying this builder.");
 DEFINE_string2(match, m, nullptr,
                "[~][^]substring[$] [...] of bench name to run.\n"
@@ -53,7 +53,6 @@
                "If a bench does not match any list entry,\n"
                "it is skipped unless some list entry starts with ~");
 DEFINE_string(skps, "skps", "Directory to read skps from.");
-DEFINE_bool(vulkan, true, "Run with Vulkan.");
 
 const char *kBackendTypeStrings[sk_app::Window::kBackendTypeCount] = {
     " [OpenGL]",
@@ -85,9 +84,6 @@
 
     SkCommandLineFlags::Parse(argc, argv);
 
-    fBackendType = FLAGS_vulkan ? sk_app::Window::kVulkan_BackendType
-                                : sk_app::Window::kNativeGL_BackendType;
-
     fWindow = Window::CreateNativeWindow(platformData);
     fWindow->attach(fBackendType, DisplayParams());
 
@@ -134,7 +130,6 @@
         this->changeZoomLevel(-1.f / 32.f);
         fWindow->inval();
     });
-#if 0  // this doesn't seem to work on any platform right now
 #ifndef SK_BUILD_FOR_ANDROID
     fCommands.addCommand('d', "Modes", "Change rendering backend", [this]() {
         fWindow->detach();
@@ -142,16 +137,14 @@
         if (sk_app::Window::kVulkan_BackendType == fBackendType) {
             fBackendType = sk_app::Window::kNativeGL_BackendType;
         } 
-        // TODO: get Vulkan -> OpenGL working on Windows without swapchain creation failure
+        // TODO: get Vulkan -> OpenGL working without swapchain creation failure
         //else if (sk_app::Window::kNativeGL_BackendType == fBackendType) {
         //    fBackendType = sk_app::Window::kVulkan_BackendType;
         //}
 
         fWindow->attach(fBackendType, DisplayParams());
         this->updateTitle();
-        fWindow->inval();
-    });
-#endif
+    });
 #endif
 
     // set up slides