CoreAnimation: Fix download shelf pattern phase

We should consider having cr_setPatternPhase make
the call to cr_viewBeingDrawnTo, but that has some
layering issues (base versus chrome), and fixing them
would be merge-unfriendly.

TBR=avi
BUG=363750

Review URL: https://codereview.chromium.org/250703003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266347 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/cocoa/download/download_shelf_view.mm

@@ -49,7 +49,8 @@
   // background matches the toolbar background.
   NSPoint phase = NSMakePoint(
       0, NSHeight([self bounds]) + [TabStripController defaultTabHeight]);
-  [[NSGraphicsContext currentContext] cr_setPatternPhase:phase forView:self];
+  [[NSGraphicsContext currentContext]
+      cr_setPatternPhase:phase forView:[self cr_viewBeingDrawnTo]];
   [self drawBackgroundWithOpaque:YES];
 
   // Draw top stroke