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, 8 insertions, 0 deletions

diff --git a/tests/PictureTest.cpp b/tests/PictureTest.cpp
index 425b25a153..4f76c6a829 100644
--- a/tests/PictureTest.cpp
+++ b/tests/PictureTest.cpp
@@ -102,6 +102,7 @@ public:
         : INHERITED(width, height)
         , fSaveCount(0)
         , fSaveLayerCount(0)
+        , fSaveBehindCount(0)
         , fRestoreCount(0){
     }
 
@@ -110,6 +111,11 @@ public:
         return this->INHERITED::getSaveLayerStrategy(rec);
     }
 
+    bool onDoSaveBehind(const SkRect* subset) override {
+        ++fSaveBehindCount;
+        return this->INHERITED::onDoSaveBehind(subset);
+    }
+
     void willSave() override {
         ++fSaveCount;
         this->INHERITED::willSave();
@@ -122,11 +128,13 @@ public:
 
     unsigned int getSaveCount() const { return fSaveCount; }
     unsigned int getSaveLayerCount() const { return fSaveLayerCount; }
+    unsigned int getSaveBehindCount() const { return fSaveBehindCount; }
     unsigned int getRestoreCount() const { return fRestoreCount; }
 
 private:
     unsigned int fSaveCount;
     unsigned int fSaveLayerCount;
+    unsigned int fSaveBehindCount;
     unsigned int fRestoreCount;
 
     typedef SkCanvas INHERITED;