Avoid passing uninitialized value to markRectAsNonOpaque.

Source/platform/graphics/GraphicsContextTest.cpp

Index: Source/platform/graphics/GraphicsContextTest.cpp
diff --git a/Source/platform/graphics/GraphicsContextTest.cpp b/Source/platform/graphics/GraphicsContextTest.cpp
index fd4a9588621b018e68224fc9756d57c97ef4e61d..7af99ec87fef43d973d0732af841fd1853d6fbfc 100644
--- a/Source/platform/graphics/GraphicsContextTest.cpp
+++ b/Source/platform/graphics/GraphicsContextTest.cpp
@@ -1042,6 +1042,77 @@ TEST(GraphicsContextTest, PreserveOpaqueOnlyMattersForFirstLayer)
     EXPECT_PIXELS_MATCH_EXACT(bitmap, context.opaqueRegion().asRect());
 }
 
+TEST(GraphicsContextTest, OpaqueRegionForLayerWithNonRectDeviceClip)
+{
+    // For non-opaque preserving mode and deviceClip is not rect
+    // we will mark opaque rect as empty.
+    Path path;
+    path.moveTo(FloatPoint(0, 0));
+    path.addLineTo(FloatPoint(50, 50));
+
+    SkCanvas canvas(400, 400);
+    GraphicsContext context(&canvas);
+
+    Color opaque(1.0f, 0.0f, 0.0f, 1.0f);
+
+    context.setRegionTrackingMode(GraphicsContext::RegionTrackingOpaque);
+
+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    EXPECT_EQ_RECT(IntRect(30, 30, 90, 90), context.opaqueRegion().asRect());
+
+    context.clipPath(path, RULE_EVENODD);
+    context.setCompositeOperation(CompositeSourceOut);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
+
+    // For opaque preserving mode and deviceClip is not rect
+    // we will not alter opaque rect.
+    context.setCompositeOperation(CompositeSourceOver);
+    context.beginTransparencyLayer(0.5);
+

[danakj, 2014/08/06 13:53:34]

If the clip was a rect, what about this begin/end layer would have made a
non-empty opaque rect?

[sohanjg, 2014/08/06 14:09:26]

yes, for rect clip, we would have got a non-empty opaque rect, but we would need
a new context for that.
shud we add 1 more test for that ?

[danakj, 2014/08/06 14:17:28]

I don't understand, the opaque rect is non-empty? But I see no fillRect or
anything of the sort here to drwa something opaque? Why do you need another
context?

[sohanjg, 2014/08/06 14:30:07]

hmm..once we set context.clipPath, it seems we cannot have any opaque region
even if do fillRect here.
To get a opaque region we need a new context, with a rect device clip here.

[danakj, 2014/08/06 14:32:10]

You can clipRect with kReplace_Op for instance?

[sohanjg, 2014/08/07 08:07:46]

I have updated the test and used rect device clip in the beginning of the test,
and later changed it by setting clippath, this addresses our test well.
hope its ok.

+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
+}
+
+TEST(GraphicsContextTest, OpaqueRegionForLayerWithRectDeviceClip)
+{
+
+    SkBitmap bitmap;
+    ASSERT_TRUE(bitmap.allocN32Pixels(400, 400));
+    bitmap.eraseColor(0);
+    SkCanvas canvas(bitmap);
+
+    Color opaque(1.0f, 0.0f, 0.0f, 1.0f);
+
+    GraphicsContext context(&canvas);
+    context.setRegionTrackingMode(GraphicsContext::RegionTrackingOpaque);
+
+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    EXPECT_EQ_RECT(IntRect(30, 30, 90, 90), context.opaqueRegion().asRect());
+
+    // For non-opaque preserving mode and deviceClip is rect
+    // we will mark device clip rect as non opaque.
+    context.setCompositeOperation(CompositeSourceOut);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
+    EXPECT_PIXELS_MATCH(bitmap, context.opaqueRegion().asRect());
+
+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+
+    // For opaque preserving mode and deviceClip is rect
+    // we will intersect device clip rect with src opaque rect.

[danakj, 2014/08/06 13:53:33]

Can you change the inputs so that we see the intersection happen by some numbers
changing? I don't see any clip here at all?

[sohanjg, 2014/08/07 08:07:46]

Done.

+    context.setCompositeOperation(CompositeSourceOver);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(30, 30, 90, 90), context.opaqueRegion().asRect());
+    EXPECT_PIXELS_MATCH(bitmap, context.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);