Make GMs aware of what tool they're being run in.

Add a saveLayer set of draws to convex_poly_clip and fix GPU bug where polygon clips don't account for the translation between clip and device space.

BUG=skia:2051
R=robertphillips@google.com, reed@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/148283017

git-svn-id: http://skia.googlecode.com/svn/trunk@13371 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 287639a..53e15a5 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -386,7 +386,9 @@
 }
 
 SkView* SkGMSampleViewFactory::operator() () const {
-    return new GMSampleView(fFunc(NULL));
+    skiagm::GM* gm = fFunc(NULL);
+    gm->setMode(skiagm::GM::kSample_Mode);
+    return new GMSampleView(gm);
 }
 
 SkViewRegister* SkViewRegister::gHead;