Avoid passing uninitialized value to markRectAsNonOpaque.

Source/platform/graphics/GraphicsContextTest.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 1024 matching lines @@
     context.setFillColor(opaque);
     path.moveTo(FloatPoint(10, 10));
     path.addLineTo(FloatPoint(40, 40));
     context.strokePath(path);
 
     context.endLayer();
     EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
     EXPECT_PIXELS_MATCH_EXACT(bitmap, context.opaqueRegion().asRect());
 }
 
+TEST(GraphicsContextTest, OpaqueRegionForLayer)
+{
+    // Set non-rect device clip.
+    Path path;
+    path.moveTo(FloatPoint(0, 0));
+    path.addLineTo(FloatPoint(50, 50));
+
+    SkCanvas canvas(50, 50);

[danakj, 2014/08/05 13:53:28]

can you make the canvas bigger than the path's bounding box, or make the path
smaller than the canvas?

[sohanjg, 2014/08/05 15:23:21]

Done.

+    GraphicsContext context(&canvas);
+    context.clipPath(path, RULE_EVENODD);
+    context.setRegionTrackingMode(GraphicsContext::RegionTrackingOpaque);
+
+    Color opaque(1.0f, 0.0f, 0.0f, 1.0f);
+
+    // Set Opaque Rect.

[danakj, 2014/08/05 13:53:28]

Say why not what, all of these comments just say what the code is doing. Instead
they should explain why they are doing what they are doing.

[sohanjg, 2014/08/05 15:23:20]

Done.

+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);

[danakj, 2014/08/05 13:53:28]

isn't this outside the bounds of the canvas?

[sohanjg, 2014/08/05 15:23:21]

Done.
I was trying to avoid markRectAsNonOpaque early-outs and get a opaque region,
but that's not imp in this test i gess.

+    // Begin non-opaque-preserving layer.
+    context.setCompositeOperation(CompositeSourceOut);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
+
+    // Set rect device clip.
+    SkBitmap bitmap;
+    ASSERT_TRUE(bitmap.allocN32Pixels(50, 50));
+    bitmap.eraseColor(0);
+    SkCanvas canvas2(bitmap);
+
+    GraphicsContext context2(&canvas2);
+    context2.setRegionTrackingMode(GraphicsContext::RegionTrackingOpaque);
+
+    // Set Opaque Rect.
+    context2.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    // Begin non-opaque-preserving layer.
+    context2.setCompositeOperation(CompositeSourceOut);
+    context2.beginTransparencyLayer(0.5);
+
+    context2.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context2.opaqueRegion().asRect());
+    EXPECT_PIXELS_MATCH(bitmap, context2.opaqueRegion().asRect());
+
+    // Set Opaque Rect.
+    context2.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    // Begin opaque-preserving layer.
+    context2.setCompositeOperation(CompositeSourceOver);
+    context2.beginTransparencyLayer(0.5);
+
+    context2.endLayer();
+    EXPECT_EQ_RECT(IntRect(30, 30, 20, 20), context2.opaqueRegion().asRect());
+    EXPECT_PIXELS_MATCH(bitmap, context2.opaqueRegion().asRect());
+}
+
 #define DISPATCH1(c1, c2, op, param1) do { c1.op(param1); c2.op(param1); } while (0);
 #define DISPATCH2(c1, c2, op, param1, param2) do { c1.op(param1, param2); c2.op(param1, param2); } while (0);
 
 TEST(GraphicsContextTest, RecordingTotalMatrix)
 {
     SkBitmap bitmap;
     ASSERT_TRUE(bitmap.allocN32Pixels(400, 400));
     bitmap.eraseColor(0);
     SkCanvas canvas(bitmap);
     GraphicsContext context(&canvas);
@@ skipping 59 matching lines @@
     EXPECT_FALSE(pic);
 
     // endRecording finally makes the picture accessible
     dl->endRecording();
     pic = dl->picture();
     EXPECT_TRUE(pic);
     EXPECT_EQ(1, pic->getRefCnt());
 }
 
 } // namespace