Add tests for the Display operation of the mac notification bridge.

chrome/browser/notifications/notification_platform_bridge_mac.mm

Index: chrome/browser/notifications/notification_platform_bridge_mac.mm
diff --git a/chrome/browser/notifications/notification_platform_bridge_mac.mm b/chrome/browser/notifications/notification_platform_bridge_mac.mm
index e96756be9d07f2003944297157bc9d80f3a2cb7c..31ab0774efde0c56369544b50d76f3ad2e73a9ce 100644
--- a/chrome/browser/notifications/notification_platform_bridge_mac.mm
+++ b/chrome/browser/notifications/notification_platform_bridge_mac.mm
@@ -91,10 +91,18 @@ NotificationPlatformBridge* NotificationPlatformBridge::Create() {
 // /////////////////////////////////////////////////////////////////////////////
 
 NotificationPlatformBridgeMac::NotificationPlatformBridgeMac(
-    NSUserNotificationCenter* notification_center)
+    NSUserNotificationCenter* notification_center) {
+  NotificationPlatformBridgeMac(notification_center, true /* set_delegate */);

[Peter Beverloo, 2016/07/11 17:25:48]

You can define a delegating constructor like:

NotificationPlatformBridgeMac::NotificationPlatformBridgeMac(
    NSUserNotificationCenter* notification_center)
    : NotificationPlatformBridgeMac(notification_center,
                                    true /* set_delegate */) {}

That said, the number of callers for NotificationPlatformBridgeMac is
sufficiently low that it'd be even better to drop the second constructor
altogether, and just always pass the boolean.

[Miguel Garcia, 2016/07/12 16:16:24]

You know I usually go with the flow with regards to following review comments
but in this case I am going to insist on keep the hack private at least :) Now
that we know why it is needed I think I will remove it the minute the dependent
roll happens.

So for now I switched to delegating constructor.

On 2016/07/11 17:25:48, Peter Beverloo wrote:

+}
+
+NotificationPlatformBridgeMac::NotificationPlatformBridgeMac(
+    NSUserNotificationCenter* notification_center,
+    bool set_delegate)
     : delegate_([NotificationCenterDelegate alloc]),
       notification_center_(notification_center) {
-  [notification_center_ setDelegate:delegate_.get()];
+  // Setting up the delegte upsets OCMock.

[Peter Beverloo, 2016/07/11 17:25:48]

delegte -> delegate

Rather than saying that it "upsets OCMock", it would be more valuable to
describe why that is an issue.

[Miguel Garcia, 2016/07/12 16:16:24]

Now that we know why sure :)

+  if (set_delegate)
+    notification_center.delegate = delegate_.get();

[Peter Beverloo, 2016/07/11 17:25:48]

Why did the syntax for the assignment change?

[Miguel Garcia, 2016/07/12 16:16:24]

It was me trying some things to keep OCMock happy, will revert.

 }
 
 NotificationPlatformBridgeMac::~NotificationPlatformBridgeMac() {