move HelloWorld to be a peer of SampleApp

This is working towards making a simple example part of the buildbot compile step and removing SkExamples from the experimental directory.

This works on Mac, Windows, and Linux but isn't complete for Android, ChromeOS and iOS.

Review URL: https://codereview.chromium.org/886413004
diff --git a/gyp/example.gyp b/gyp/example.gyp
new file mode 100644
index 0000000..34a7982
--- /dev/null
+++ b/gyp/example.gyp
@@ -0,0 +1,51 @@
+# GYP file to build hello world example.
+{
+  'targets': [
+    {
+      'target_name': 'HelloWorld',
+      'type': 'executable',
+      'mac_bundle' : 1,
+      'include_dirs' : [
+        '../include/gpu',
+      ],
+      'sources': [
+        '../example/HelloWorld.h',
+        '../example/HelloWorld.cpp',
+      ],
+      'dependencies': [
+        'skia_lib.gyp:skia_lib',
+        'views.gyp:views',
+      ],
+      'conditions' : [
+        [ 'skia_os == "win"', {
+          'sources' : [
+            '../src/views/win/SkOSWindow_Win.cpp',
+            '../src/views/win/skia_win.cpp',
+          ],
+        }],
+        [ 'skia_os == "mac"', {
+          'sources': [
+            '../example/mac/HelloWorldNSView.mm',
+            '../example/mac/HelloWorldDelegate.mm',
+
+            '../src/views/mac/SkEventNotifier.mm',
+            '../src/views/mac/skia_mac.mm',
+            '../src/views/mac/SkNSView.mm',
+            '../src/views/mac/SkOptionsTableView.mm',
+            '../src/views/mac/SkOSWindow_Mac.mm',
+            '../src/views/mac/SkTextFieldCell.m',
+          ],
+          'include_dirs' : [
+            '../src/views/mac/'
+          ],
+          'xcode_settings' : {
+            'INFOPLIST_FILE' : '../example/mac/HelloWorld-Info.plist',
+          },
+          'mac_bundle_resources' : [
+            '../example/mac/HelloWorld.xib'
+          ],
+        }],
+      ],
+    },
+  ],
+}