Disable proxy config button and show banner if proxy prefs are managed.

chrome/browser/cocoa/preferences_window_controller.mm

Index: chrome/browser/cocoa/preferences_window_controller.mm
diff --git a/chrome/browser/cocoa/preferences_window_controller.mm b/chrome/browser/cocoa/preferences_window_controller.mm
index 0aa15010736f47fa265006e704c8574dbde7a1fc..d7ec2de9f6e7d298cf9fcd2567885a00a48ae125 100644
--- a/chrome/browser/cocoa/preferences_window_controller.mm
+++ b/chrome/browser/cocoa/preferences_window_controller.mm
@@ -416,6 +416,8 @@ class ManagedPrefsBannerState : public ManagedPrefsBannerBase {
 
 @implementation PreferencesWindowController
 
+@synthesize proxiesConfigureButtonEnabled = proxiesConfigureButtonEnabled_;
+
 - (id)initWithProfile:(Profile*)profile initialPage:(OptionsPage)initialPage {
   DCHECK(profile);
   // Use initWithWindowNibPath:: instead of initWithWindowNibName: so we
@@ -483,6 +485,11 @@ class ManagedPrefsBannerState : public ManagedPrefsBannerBase {
     PersonalDataManager* personalDataManager =
         profile_->GetPersonalDataManager();
     [autoFillSettingsButton_ setHidden:(personalDataManager == NULL)];
+
+    // Initialize the proxy pref set observer.
+    proxyPrefs_.reset(
+        PrefSetObserver::CreateProxyPrefSetObserver(prefs_, observer_.get()));
+    [self setProxiesConfigureButtonEnabled:!proxyPrefs_->IsManaged()];
   }
   return self;
 }
@@ -1380,6 +1387,9 @@ const int kDisabledIndex = 1;
     // Poke KVC.
     [self setFileHandlerUIEnabled:[self fileHandlerUIEnabled]];
   }
+  else if (proxyPrefs_->IsObserved(*prefName)) {
+    [self setProxiesConfigureButtonEnabled:!proxyPrefs_->IsManaged()];
+  }
 }
 
 // Set the new download path and notify the UI via KVO.