add --forceRasterPipeline to dm, (already in nanobench)

Bug: skia:
Change-Id: I0e5f7dd2aaa03340687cdfe5578c8697088cd714
Reviewed-on: https://skia-review.googlesource.com/21532
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 18645a1..3ddc827 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -54,6 +54,8 @@
     #include <unistd.h>
 #endif
 
+extern bool gSkForceRasterPipelineBlitter;
+
 DEFINE_string(src, "tests gm skp image", "Source types to test.");
 DEFINE_bool(nameByHash, false,
             "If true, write to FLAGS_writePath[0]/<hash>.png instead of "
@@ -79,6 +81,7 @@
 DEFINE_int32(shard,  0, "Which shard do I run?");
 
 DEFINE_string(mskps, "", "Directory to read mskps from, or a single mskp file.");
+DEFINE_bool(forceRasterPipeline, false, "sets gSkForceRasterPipelineBlitter");
 
 #if SK_SUPPORT_GPU
 DEFINE_pathrenderer_flag;
@@ -1270,6 +1273,9 @@
     if (FLAGS_forceAnalyticAA) {
         gSkForceAnalyticAA = true;
     }
+    if (FLAGS_forceRasterPipeline) {
+        gSkForceRasterPipelineBlitter = true;
+    }
 
     // The bots like having a verbose.log to upload, so always touch the file even if --verbose.
     if (!FLAGS_writePath.isEmpty()) {