Avoid passing uninitialized value to markRectAsNonOpaque.

Source/platform/graphics/skia/OpaqueRegionSkia.cpp

Index: Source/platform/graphics/skia/OpaqueRegionSkia.cpp
diff --git a/Source/platform/graphics/skia/OpaqueRegionSkia.cpp b/Source/platform/graphics/skia/OpaqueRegionSkia.cpp
index 24c0369d2ee641c597367d4f4541d6d0d6364fa1..58ca5303f433851a299b64028bd6e9fbc4e1dcdb 100644
--- a/Source/platform/graphics/skia/OpaqueRegionSkia.cpp
+++ b/Source/platform/graphics/skia/OpaqueRegionSkia.cpp
@@ -156,8 +156,10 @@ static inline bool paintIsOpaque(const SkPaint& paint, OpaqueRegionSkia::DrawTyp
 static inline bool getDeviceClipAsRect(const GraphicsContext* context, SkRect& deviceClipRect)
 {
     // Get the current clip in device coordinate space.
-    if (!context->canvas()->isClipRect())
+    if (!context->canvas()->isClipRect()) {
+        deviceClipRect.setEmpty();
         return false;
+    }
 
     SkIRect deviceClipIRect;
     if (context->canvas()->getClipDeviceBounds(&deviceClipIRect))
@@ -331,7 +333,7 @@ void OpaqueRegionSkia::applyOpaqueRegionFromLayer(const GraphicsContext* context
     SkRect deviceClipRect;
     bool deviceClipIsARect = getDeviceClipAsRect(context, deviceClipRect);
 
-    if (deviceClipRect.isEmpty())
+    if (deviceClipIsARect && deviceClipRect.isEmpty())
         return;
 
     SkRect sourceOpaqueRect = layerOpaqueRect;
@@ -339,11 +341,14 @@ void OpaqueRegionSkia::applyOpaqueRegionFromLayer(const GraphicsContext* context
     SkRect destinationOpaqueRect = currentTrackingOpaqueRect();
 
     bool outsideSourceOpaqueRectPreservesOpaque = xfermodePreservesOpaque(paint, false);
-    if (!outsideSourceOpaqueRectPreservesOpaque)
+    if (!outsideSourceOpaqueRectPreservesOpaque) {
+        if (!deviceClipIsARect) {
+            markAllAsNonOpaque();
+            return;
+        }
         markRectAsNonOpaque(deviceClipRect);
+    }
 
-    if (!deviceClipIsARect)

[danakj, 2014/07/30 13:31:26]

We've lost this early out in some cases now. Can you fix that and add a test
case for it?

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

Done.

-        return;
     if (!sourceOpaqueRect.intersect(deviceClipRect))
         return;