Update avatar button when profile count changes

The generic icon should be shown when there's only one (non-signed in)
user. We need to listen for add/remove profile events so we can detect
whether a generic icon should be shown or not for existing windows as
well.

Bug: chromium:822070
Change-Id: Ia84feb13dd10b4459aeff326e2fd6e1d29698a76
Reviewed-on: https://chromium-review.googlesource.com/1028981Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553912}

chrome/browser/ui/views/profiles/avatar_toolbar_button.cc

@@ -71,6 +71,20 @@ void AvatarToolbarButton::OnAvatarErrorChanged() {
   UpdateIcon();
 }
 
+void AvatarToolbarButton::OnProfileAdded(const base::FilePath& profile_path) {
+  // Adding any profile changes the profile count, we might go from showing a
+  // generic avatar button to profile pictures here. Update icon accordingly.
+  UpdateIcon();
+}
+
+void AvatarToolbarButton::OnProfileWasRemoved(
+    const base::FilePath& profile_path,
+    const base::string16& profile_name) {
+  // Removing a profile changes the profile count, we might go from showing
+  // per-profile icons back to a generic avatar icon. Update icon accordingly.
+  UpdateIcon();
+}
+
 void AvatarToolbarButton::OnProfileAvatarChanged(
     const base::FilePath& profile_path) {
   UpdateIcon();

chrome/browser/ui/views/profiles/avatar_toolbar_button.h

@@ -27,6 +27,9 @@ class AvatarToolbarButton : public ToolbarButton,
   void OnAvatarErrorChanged() override;
 
   // ProfileAttributesStorage::Observer:
+  void OnProfileAdded(const base::FilePath& profile_path) override;
+  void OnProfileWasRemoved(const base::FilePath& profile_path,
+                           const base::string16& profile_name) override;
   void OnProfileAvatarChanged(const base::FilePath& profile_path) override;
   void OnProfileHighResAvatarLoaded(
       const base::FilePath& profile_path) override;