use platform-independent font for gm

samplecode/SampleApp.cpp

Index: samplecode/SampleApp.cpp
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 2a4ebdce4117aed216dce1927dfc0aad0e37d459..df10b1e70bec2b31e31ed9d3fb6a8568a400ae37 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -1685,6 +1685,10 @@ static void cleanup_for_filename(SkString* name) {
 }
 #endif
 
+namespace sk_tool_utils {
+    extern bool gEnablePortableTypeface;
+};
+
 bool SampleWindow::onHandleChar(SkUnichar uni) {
     {
         SkView* view = curr_view(this);
@@ -1738,6 +1742,10 @@ bool SampleWindow::onHandleChar(SkUnichar uni) {
             // only
             toggleFPS();
             break;
+        case 'F':
+            sk_tool_utils::gEnablePortableTypeface ^= true;
+            this->inval(NULL);
+            break;
         case 'g':
             fRequestGrabImage = true;
             this->inval(NULL);