Prepare ui/ module for compilation with OS X 10.7 deployment target.

ui/base/cocoa/base_view.mm

Index: ui/base/cocoa/base_view.mm
diff --git a/ui/base/cocoa/base_view.mm b/ui/base/cocoa/base_view.mm
index 9642fbe1a81f3b8bf64a6853ab441af32c30194c..a37b049793dd390e2ad266cb2f2db37eab9906e0 100644
--- a/ui/base/cocoa/base_view.mm
+++ b/ui/base/cocoa/base_view.mm
@@ -170,19 +170,6 @@ NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
     [super keyUp:theEvent];
 }
 
-- (void)pressureChangeWithEvent:(NSEvent*)theEvent {
-  NSInteger newStage = [theEvent stage];
-  if (pressureEventStage_ == newStage)
-    return;
-
-  // Call the force touch event when the stage reaches 2, which is the value
-  // for force touch.
-  if (newStage == 2) {
-    [self forceTouchEvent:theEvent];

[Avi (use Gerrit), 2016/03/08 20:07:54]

I'm rather uncomfortable here. While it seems like no one is calling
-pressureChangeWithEvent:, this call to -forceTouchEvent: seems to be overridden
in RenderWidgetHostViewMac (see
https://code.google.com/p/chromium/codesearch#search/&q=forceTouchEvent ).
Either this should somehow be hooked in, or the other code should be removed.

[Avi (use Gerrit), 2016/03/08 20:13:08]

OK, I'm really unsure about this. -pressureChangeWithEvent: seems to be the hook
for Force Touch (see
http://www.metaltoad.com/blog/use-the-force-touch-mac-programming ,
https://gregheo.com/blog/force-touch/ , and
https://webkit.googlesource.com/WebKit/+/dc0d9c76834640b3f2c9a180cf2e1ff5e8aa...
).

[erikchen, 2016/03/08 20:57:41]

Whoops! Good catch. 

-  }
-  pressureEventStage_ = newStage;

[Avi (use Gerrit), 2016/03/08 20:07:54]

pressureEventStage_ is only used in this method; if we remove this method remove
the variable from the class definition in the .h file.

-}
-
 - (void)flagsChanged:(NSEvent*)theEvent {
   if ([self keyEvent:theEvent] != kEventHandled)
     [super flagsChanged:theEvent];