Support mesa config in render_pictures.

tools/PictureRenderingFlags.cpp

Index: tools/PictureRenderingFlags.cpp
===================================================================
--- tools/PictureRenderingFlags.cpp	(revision 12915)
+++ tools/PictureRenderingFlags.cpp	(working copy)
@@ -25,14 +25,18 @@
               "playbackCreation.");
 // Although this config does not support all the same options as gm, the names should be kept
 // consistent.
+DEFINE_string(config, "8888", "["
+              "8888"
+#if SK_SUPPORT_GPU
+              "|gpu|msaa4|msaa16"
+#endif
 #if SK_ANGLE
-// ANGLE assumes GPU
-DEFINE_string(config, "8888", "[8888|gpu|msaa4|msaa16|angle]: Use the corresponding config.");
-#elif SK_SUPPORT_GPU
-DEFINE_string(config, "8888", "[8888|gpu|msaa4|msaa16]: Use the corresponding config.");
-#else
-DEFINE_string(config, "8888", "[8888]: Use the corresponding config.");
+              "|angle"
 #endif
+#if SK_MESA
+              "|mesa"
+#endif
+              "]: Use the corresponding config.");
 
 DEFINE_bool(deferImageDecoding, false, "Defer decoding until drawing images. "
             "Has no effect if the provided skp does not have its images encoded.");
@@ -285,7 +289,16 @@
             }
         }
 #endif
+#if SK_MESA
+        else if (0 == strcmp(FLAGS_config[0], "mesa")) {
+            deviceType = sk_tools::PictureRenderer::kMesa_DeviceType;
+            if (FLAGS_multi > 1) {
+                error.printf("Mesa not compatible with multithreaded tiling.\n");
+                return NULL;
+            }
+        }
 #endif
+#endif
         else {
             error.printf("%s is not a valid mode for --config\n", FLAGS_config[0]);
             return NULL;