Add line height setting to views::Label & use it for notifications.

ui/gfx/canvas_mac.mm

Index: ui/gfx/canvas_mac.mm
diff --git a/ui/gfx/canvas_mac.mm b/ui/gfx/canvas_mac.mm
index bb99c0666c28cb67352d07217eba3d01361bf633..ec0e2fa4423e441c707ca7ccadce3bf482a66ce3 100644
--- a/ui/gfx/canvas_mac.mm
+++ b/ui/gfx/canvas_mac.mm
@@ -40,6 +40,7 @@ void Canvas::SizeStringInt(const string16& text,
                            const gfx::Font& font,
                            int* width,
                            int* height,
+                           int line_height,  // Ignored for now.

[dharcourt, 2013/04/17 17:52:21]

Since multi-line isn't implemented for canvas_mac, line_height naturally won't
be, so I removed the comment here and updated the multi-line comment above.

                            int flags) {
   NSFont* native_font = font.GetNativeFont();
   NSString* ns_string = base::SysUTF16ToNSString(text);
@@ -55,6 +56,7 @@ void Canvas::DrawStringWithShadows(const string16& text,
                                    const gfx::Font& font,
                                    SkColor color,
                                    const gfx::Rect& text_bounds,
+                                   int line_height,  // Ignored for now.
                                    int flags,
                                    const ShadowValues& shadows) {
   DLOG_IF(WARNING, !shadows.empty()) << "Text shadow not implemented.";