[Chromoting] Let the Mac host policy watcher read string-valued policies.

remoting/host/policy_hack/policy_watcher_mac.mm

Index: remoting/host/policy_hack/policy_watcher_mac.mm
diff --git a/remoting/host/policy_hack/policy_watcher_mac.mm b/remoting/host/policy_hack/policy_watcher_mac.mm
index 26b3213f20bf246acb7dd2bac1778f9357113c19..d0dd47322168ec526d3bb623391853d5c18d00ad 100644
--- a/remoting/host/policy_hack/policy_watcher_mac.mm
+++ b/remoting/host/policy_hack/policy_watcher_mac.mm
@@ -7,6 +7,7 @@
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/compiler_specific.h"
+#include "base/mac/foundation_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/single_thread_task_runner.h"
@@ -56,7 +57,23 @@ class PolicyWatcherMac : public PolicyWatcher {
           policy.SetBoolean(policy_name, allowed);
         }
       }
-      // TODO(simonmorris): Read policies whose names are in kStringPolicyNames.
+      for (int i = 0; i < kStringPolicyNamesNum; ++i) {
+        const char* policy_name = kStringPolicyNames[i];
+        base::mac::ScopedCFTypeRef<CFStringRef> policy_key(
+            base::SysUTF8ToCFStringRef(policy_name));
+        base::mac::ScopedCFTypeRef<CFPropertyListRef> property_list(
+            CFPreferencesCopyAppValue(policy_key, policy_bundle_id));
+        if (property_list.get() != NULL) {
+          CFStringRef policy_value = base::mac::CFCast<CFStringRef>(
+              property_list.get());
+          if (policy_value != NULL) {
+            policy.SetString(policy_name,
+                             base::SysCFStringRefToUTF8(policy_value));
+          } else {
+            LOG(WARNING) << "Policy " << policy_name << ": value not a string.";
+          }
+        }
+      }
     }
 
     // Set policy. Policy must be set (even if it is empty) so that the