Add GrSurface::savePixels().

src/gpu/GrSurface.cpp

Index: src/gpu/GrSurface.cpp
diff --git a/src/gpu/GrSurface.cpp b/src/gpu/GrSurface.cpp
index 47d9959d26723a1e6adf5cd75cabfc59a7e7ef45..e14987f083c483e00bb315aca994dbbbd9b529d5 100644
--- a/src/gpu/GrSurface.cpp
+++ b/src/gpu/GrSurface.cpp
@@ -7,4 +7,31 @@
 
 #include "GrSurface.h"
 
+#include "SkBitmap.h"
+#include "SkImageEncoder.h"
+
 SK_DEFINE_INST_COUNT(GrSurface)
+
+bool GrSurface::savePixels(const char* filename) {
+    SkBitmap bm;
+    bm.setConfig(SkBitmap::kARGB_8888_Config, this->width(), this->height());
+    bm.allocPixels();
+
+    bool result = readPixels(0, 0, this->width(), this->height(), kSkia8888_GrPixelConfig, 
+                             bm.getPixels());
+    if (!result) {
+        SkDebugf("------ failed to read pixels for %s\n", filename);
+        return false;
+    }
+    
+    // remove any previous version of this file
+    remove(filename);
+
+    if (!SkImageEncoder::EncodeFile(filename, bm, SkImageEncoder::kPNG_Type, 100)) {
+        SkDebugf("------ failed to encode %s\n", filename);
+        remove(filename);   // remove any partial file
+        return false;
+    }
+
+    return true;
+}