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 8a76411d237a15b582ddd7cff8e05f0add7e1aec..739f1a91b7dc1d1813efc5883767d7c0bdd70918 100644
--- a/Source/platform/graphics/GraphicsContextTest.cpp
+++ b/Source/platform/graphics/GraphicsContextTest.cpp
@@ -1042,6 +1042,40 @@ TEST(GraphicsContextTest, PreserveOpaqueOnlyMattersForFirstLayer)
     EXPECT_PIXELS_MATCH_EXACT(bitmap, context.opaqueRegion().asRect());
 }
 
+TEST(GraphicsContextTest, OpaqueRegionForLayer)
+{
+    SkBitmap bitmap;

[danakj, 2014/07/30 13:31:25]

What makes the device clip not a Rect in this test?

[sohanjg, 2014/07/30 13:41:54]

This is still a Rect, i wonder how can we set device clip as non rect ?
This test will only cover markRectAsNonOpaque(deviceClipRect) code, and not the
markAllAsNonOpaque() code.

[sohanjg, 2014/07/31 15:44:34]

Done.

+    ASSERT_TRUE(bitmap.allocN32Pixels(100, 100));
+    bitmap.eraseColor(0);
+    SkCanvas canvas(bitmap);
+
+    GraphicsContext context(&canvas);
+    context.setTrackOpaqueRegion(true);
+
+    Path path;
+    Color opaque(1.0f, 0.0f, 0.0f, 1.0f);
+
+    // Set Opaque Rect.
+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    // Begin non-opaque-preserving layer.
+    context.setCompositeOperation(CompositeSourceOut);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(), context.opaqueRegion().asRect());
+    EXPECT_PIXELS_MATCH_EXACT(bitmap, context.opaqueRegion().asRect());
+
+    // Set Opaque Rect.
+    context.fillRect(FloatRect(30, 30, 90, 90), opaque, CompositeSourceOver);
+    // Begin opaque-preserving layer.
+    context.setCompositeOperation(CompositeSourceOver);
+    context.beginTransparencyLayer(0.5);
+
+    context.endLayer();
+    EXPECT_EQ_RECT(IntRect(30, 30, 70, 70), 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);