cc: Add LayerTreeSetting to disable cached picture raster.

cc/layers/picture_image_layer.cc

Index: cc/layers/picture_image_layer.cc
diff --git a/cc/layers/picture_image_layer.cc b/cc/layers/picture_image_layer.cc
index 3c17c8c3bbae66f9607a31e4161e7e4793f89377..243223909e4af1ba0cc7b410028ee7701aa602df 100644
--- a/cc/layers/picture_image_layer.cc
+++ b/cc/layers/picture_image_layer.cc
@@ -6,6 +6,8 @@
 
 #include <stddef.h>
 
+#include "base/command_line.h"
+#include "cc/base/switches.h"
 #include "cc/layers/picture_image_layer_impl.h"
 #include "cc/playback/display_item_list_settings.h"
 #include "cc/playback/drawing_display_item.h"
@@ -16,6 +18,15 @@
 
 namespace cc {
 
+namespace {
+
+static bool UseCachedPictureRaster() {

[vmpstr, 2016/03/25 21:45:12]

Is it possible to plumb this through layer tree settings? I don't really want to
set the precedent of checking the command line in our layers... The
web_content_layer_impl is kind of the blink interface, so I'm not sure if they
can access layer tree settings.

[Khushal, 2016/03/25 21:53:48]

Sure I can add a LayerTreeSetting for this. Yup, cc/blink wouldn't have any
access to it, so we would have to use the command line flag there.

+  static bool use = !base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableCachedPictureRaster);
+  return use;
+}
+}
+
 scoped_refptr<PictureImageLayer> PictureImageLayer::Create() {
   return make_scoped_refptr(new PictureImageLayer());
 }
@@ -58,10 +69,8 @@ scoped_refptr<DisplayItemList> PictureImageLayer::PaintContentsToDisplayList(
   DCHECK_GT(image_->width(), 0);
   DCHECK_GT(image_->height(), 0);
 
-  // Picture image layers can be used with GatherPixelRefs, so cached SkPictures
-  // are currently required.
   DisplayItemListSettings settings;
-  settings.use_cached_picture = true;
+  settings.use_cached_picture = UseCachedPictureRaster();
   scoped_refptr<DisplayItemList> display_list =
       DisplayItemList::Create(PaintableRegion(), settings);