Resubmit issue 2221103002 to fix the iOS build by declaring the flag in
SkCommonFlags.h

TBR=reed@google.com,caryclark@google.com

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2393643002

Review-Url: https://codereview.chromium.org/2393643002
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 233306c..385268e 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -33,6 +33,7 @@
 #include "SkTypeface.h"
 #include "SkWindow.h"
 #include "sk_tool_utils.h"
+#include "SkScan.h"
 
 #include "SkReadBuffer.h"
 #include "SkStream.h"
@@ -1800,6 +1801,11 @@
                 this->inval(nullptr);
             }
             break;
+        case 'A':
+            GlobalAAConfig::getInstance().fUseAnalyticAA =
+                    !GlobalAAConfig::getInstance().fUseAnalyticAA;
+            this->inval(nullptr);
+            break;
         case 'B':
             post_event_to_sink(new SkEvent("PictFileView::toggleBBox"), curr_view(this));
             // Cannot call updateTitle() synchronously, because the toggleBBox event is still in