Add private save-behind and draw-behind methods to canvas.HEADp9.0

The draw-behind  is a variant of drawPaint but is automatically clipped
to the bounds of the most recent saveBehind buffer (axis-aligned bounds).

No public exposure outside of the Android framework.

Impl is pretty simple (its a variant of drawPaint)
- find the most recent saveBehind device bounds
- if there is none, draw nothing, else
  - temporarily intersect the device's clip with that bounds
  - drawPaint
  - restore the clip

This patches did not apply cleanly and have been updated to compile
with a previous version of Skia. It was cherry-picked from the
following 3 Skia commits:
148b7fd3ad9c29dec0052de624c26ff291ef8f0a
d567408362bf7847d6000f6786f9a7b2c9d0b88b
9adc82c73df0ef25b708cae8aa48ef9c39ed4c67

Bug: 129117085
Test: None
Change-Id: I291f57885de6e95f749bf5cdb70ac16a5781ffb1

1 files changed, 5 insertions, 0 deletions

diff --git a/tools/debugger/SkDebugCanvas.cpp b/tools/debugger/SkDebugCanvas.cpp
index 0bfd85f7f9..7557faa0c8 100644
--- a/tools/debugger/SkDebugCanvas.cpp
+++ b/tools/debugger/SkDebugCanvas.cpp
@@ -616,6 +616,11 @@ SkCanvas::SaveLayerStrategy SkDebugCanvas::getSaveLayerStrategy(const SaveLayerR
     return kNoLayer_SaveLayerStrategy;
 }
 
+bool SkDebugCanvas::onDoSaveBehind(const SkRect* subset) {
+    // TODO
+    return false;
+}
+
 void SkDebugCanvas::didSetMatrix(const SkMatrix& matrix) {
     this->addDrawCommand(new SkSetMatrixCommand(matrix));
     this->INHERITED::didSetMatrix(matrix);