cc: Add image decode control in the compositor.

cc/playback/discardable_image_map.h

Index: cc/playback/discardable_image_map.h
diff --git a/cc/playback/discardable_image_map.h b/cc/playback/discardable_image_map.h
index 0306e1b7e526bf1e2e1648766f90a3b309413281..7682601562f115ca7ef6d194c889dce63a489994 100644
--- a/cc/playback/discardable_image_map.h
+++ b/cc/playback/discardable_image_map.h
@@ -20,6 +20,22 @@ class SkImage;
 
 namespace cc {
 
+// Helper function to apply the matrix to the rect and return the result.
+SkRect MapRect(const SkMatrix& matrix, const SkRect& src);
+
+// Helper funciton to extract a scale from the matrix. Returns true on success
+// and false on failure.
+bool ExtractScale(const SkMatrix& matrix, SkSize* scale);
+
+// Helper function to compute the new rect bounds adjusted for both the current
+// paint and all of the saved paints. Returns true on success and false on
+// failure.
+bool ComputeNewRectFromPaintBounds(

[ericrk, 2015/12/08 21:34:26]

nit: name is a bit weird, as we are producing paint_bounds, but the funciton is
called ....FromPaintBounds - which makes it feel like this would be an in
parameter.

[vmpstr, 2015/12/09 23:53:41]

Renamed.

+    const SkRect& rect,
+    const SkPaint* paint,

[enne (OOO), 2015/12/08 23:27:24]

Maybe calling this arg "current_paint" would also help with clarity.

[vmpstr, 2015/12/09 23:53:41]

Done.

+    const std::vector<const SkPaint*>& saved_paints,
+    SkRect* paint_bounds);
+
 // This class is used for generating discardable images data (see DrawImage
 // for the type of data it stores). It allows the client to query a particular
 // rect and get back a list of DrawImages in that rect.