[Mac] Allow NSExceptions in third-party webcam code.

Chromium cannot control that code, and NSExceptions should be safe-ish
since there is no Chromium code on the stack.

BUG=174708


Review URL: https://chromiumcodereview.appspot.com/12208053

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181417 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 18 insertions, 0 deletions

diff --git a/base/mac/scoped_nsexception_enabler.h b/base/mac/scoped_nsexception_enabler.h
index e1d0b3c..e28e516 100644
--- a/base/mac/scoped_nsexception_enabler.h
+++ b/base/mac/scoped_nsexception_enabler.h
@@ -45,8 +45,15 @@ BASE_EXPORT void SetNSExceptionsAllowed(bool allowed);
 // Executes [target performSelector:sel] with fatal-exceptions turned
 // off, and returns the result.  If an exception is thrown during the
 // perform, nil is returned.
+// TODO(shess): Deprecated, convert to RunBlockIgnoringExceptions().
 BASE_EXPORT id PerformSelectorIgnoringExceptions(NSObject* target, SEL sel);
 
+// Executes |block| with fatal-exceptions turned off, and returns the
+// result.  If an exception is thrown during the perform, nil is
+// returned.
+typedef id (^BlockReturningId)();
+BASE_EXPORT id RunBlockIgnoringExceptions(BlockReturningId block);
+
 }  // namespace mac
 }  // namespace base
 
diff --git a/base/mac/scoped_nsexception_enabler.mm b/base/mac/scoped_nsexception_enabler.mm
index 9898789..44d4e19 100644
--- a/base/mac/scoped_nsexception_enabler.mm
+++ b/base/mac/scoped_nsexception_enabler.mm
@@ -50,6 +50,17 @@ id PerformSelectorIgnoringExceptions(NSObject* target, SEL sel) {
   return ret;
 }
 
+id RunBlockIgnoringExceptions(BlockReturningId block) {
+  id ret = nil;
+  @try {
+    base::mac::ScopedNSExceptionEnabler enable;
+    ret = block();
+  }
+  @catch(id exception) {
+  }
+  return ret;
+}
+
 ScopedNSExceptionEnabler::ScopedNSExceptionEnabler() {
   was_enabled_ = GetNSExceptionsAllowed();
   SetNSExceptionsAllowed(true);