skia: Avoid drawing of images completely in PaintSimplifier.

Images are expensive to draw, especially when they need to be
scaled. This skips draw operations with images completely to
ensure that drawing using the PaintSimplifier has a predictable
cost.

BUG=

Review URL: https://codereview.chromium.org/310643004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274642 0039d316-1c4b-4281-b951-d872f2087c98

skia/ext/paint_simplifier.cc

@@ -4,8 +4,23 @@
 
 #include "skia/ext/paint_simplifier.h"
 #include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/core/SkShader.h"
 
 namespace skia {
+namespace {
+
+bool PaintHasBitmap(const SkPaint &paint) {
+  SkShader* shader = paint.getShader();
+  if (!shader)
+    return false;
+
+  if (shader->asAGradient(NULL) == SkShader::kNone_GradientType)
+    return false;
+
+  return shader->asABitmap(NULL, NULL, NULL) != SkShader::kNone_BitmapType;
+}
+
+}  // namespace
 
 PaintSimplifier::PaintSimplifier()
   : INHERITED() {
@@ -17,6 +32,9 @@ PaintSimplifier::~PaintSimplifier() {
 }
 
 bool PaintSimplifier::filter(SkPaint* paint, Type type) {
+  // Bitmaps are expensive. Skip draw if type has a bitmap.
+  if (type == kBitmap_Type || PaintHasBitmap(*paint))
+    return false;
 
   // Preserve a modicum of text quality; black & white text is
   // just too blocky, even during a fling.