Fix the problem that notifications and panels overlap.

chrome/browser/notifications/balloon_collection_mac.mm

Index: chrome/browser/notifications/balloon_collection_mac.mm
diff --git a/chrome/browser/notifications/balloon_collection_mac.mm b/chrome/browser/notifications/balloon_collection_mac.mm
index d31bc399ddb5a1c6138e930cfccdbdd87805098a..8ff3c8fa1abbe2b559cda1603bbaa6ef3e1acabe 100644
--- a/chrome/browser/notifications/balloon_collection_mac.mm
+++ b/chrome/browser/notifications/balloon_collection_mac.mm
@@ -35,6 +35,14 @@ int BalloonCollectionImpl::Layout::VerticalEdgeMargin() const {
   return 0;
 }
 
+bool BalloonCollectionImpl::Layout::NeedToMoveAboveLeftSidePanels() const {
+  return placement_ == VERTICALLY_FROM_TOP_LEFT;
+}
+
+bool BalloonCollectionImpl::Layout::NeedToMoveAboveRightSidePanels() const {
+  return placement_ == VERTICALLY_FROM_TOP_RIGHT;
+}
+
 void BalloonCollectionImpl::PositionBalloons(bool reposition) {
   // Use an animation context so that all the balloons animate together.
   [NSAnimationContext beginGrouping];
@@ -61,6 +69,7 @@ void BalloonCollectionImpl::SetPositionPreference(
   else
     NOTREACHED();
 
+  layout_.ComputeOffsetToMoveAbovePanels(gfx::Rect());
   PositionBalloons(true);
 }