Remove base/mac/scoped_nsexception_enabler.h.

Exception fatalisation is now handled via base::mac::CallWithEHFrame, so
this file is unnecessary.

The base::mac::ScopedNSExceptionEnabler is removed, since instantiating an
NSException is no longer fatal (only an uncaught one is).
base::mac::RunBlockIgnoringExceptions has been removed where possible or converted
to a @try/@catch to swallow any exceptions.

BUG=503128
R=shess@chromium.org

Review URL: https://codereview.chromium.org/1233983004

Cr-Commit-Position: refs/heads/master@{#339884}

12 files changed, 24 insertions, 177 deletions

diff --git a/base/BUILD.gn b/base/BUILD.gn
index 6866707..23cc60f 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -306,8 +306,6 @@ component("base") {
     "mac/scoped_mach_vm.h",
     "mac/scoped_nsautorelease_pool.h",
     "mac/scoped_nsautorelease_pool.mm",
-    "mac/scoped_nsexception_enabler.h",
-    "mac/scoped_nsexception_enabler.mm",
     "mac/scoped_nsobject.h",
     "mac/scoped_objc_class_swizzler.h",
     "mac/scoped_objc_class_swizzler.mm",
diff --git a/base/base.gypi b/base/base.gypi
index 0d0b8e1..efe67c0 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -317,8 +317,6 @@
           'mac/scoped_mach_vm.h',
           'mac/scoped_nsautorelease_pool.h',
           'mac/scoped_nsautorelease_pool.mm',
-          'mac/scoped_nsexception_enabler.h',
-          'mac/scoped_nsexception_enabler.mm',
           'mac/scoped_nsobject.h',
           'mac/scoped_objc_class_swizzler.h',
           'mac/scoped_objc_class_swizzler.mm',
diff --git a/base/mac/scoped_nsexception_enabler.h b/base/mac/scoped_nsexception_enabler.h
deleted file mode 100644
index 484dd53..0000000
--- a/base/mac/scoped_nsexception_enabler.h
+++ /dev/null
@@ -1,54 +0,0 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_MAC_SCOPED_NSEXCEPTION_ENABLER_H_
-#define BASE_MAC_SCOPED_NSEXCEPTION_ENABLER_H_
-
-#import <Foundation/Foundation.h>
-
-#include "base/base_export.h"
-#include "base/basictypes.h"
-
-namespace base {
-namespace mac {
-
-// BrowserCrApplication attempts to restrict throwing of NSExceptions
-// because they interact badly with C++ scoping rules.  Unfortunately,
-// there are some cases where exceptions must be supported, such as
-// when third-party printer drivers are used.  These helpers can be
-// used to enable exceptions for narrow windows.
-
-// Make it easy to safely allow NSException to be thrown in a limited
-// scope.  Note that if an exception is thrown, then this object will
-// not be appropriately destructed!  If the exception ends up in the
-// top-level event loop, things are cleared in -reportException:.  If
-// the exception is caught at a lower level, a higher level scoper
-// should eventually reset things.
-class BASE_EXPORT ScopedNSExceptionEnabler {
- public:
-  ScopedNSExceptionEnabler();
-  ~ScopedNSExceptionEnabler();
-
- private:
-  bool was_enabled_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedNSExceptionEnabler);
-};
-
-// Access the exception setting for the current thread.  This is for
-// the support code in BrowserCrApplication, other code should use
-// the scoper.
-BASE_EXPORT bool GetNSExceptionsAllowed();
-BASE_EXPORT void SetNSExceptionsAllowed(bool allowed);
-
-// 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
-
-#endif  // BASE_MAC_SCOPED_NSEXCEPTION_ENABLER_H_
diff --git a/base/mac/scoped_nsexception_enabler.mm b/base/mac/scoped_nsexception_enabler.mm
deleted file mode 100644
index 7b8ad92..0000000
--- a/base/mac/scoped_nsexception_enabler.mm
+++ /dev/null
@@ -1,63 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#import "base/mac/scoped_nsexception_enabler.h"
-
-#import "base/lazy_instance.h"
-#import "base/threading/thread_local.h"
-
-// To make the |g_exceptionsAllowed| declaration readable.
-using base::LazyInstance;
-using base::ThreadLocalBoolean;
-
-// When C++ exceptions are disabled, the C++ library defines |try| and
-// |catch| so as to allow exception-expecting C++ code to build properly when
-// language support for exceptions is not present.  These macros interfere
-// with the use of |@try| and |@catch| in Objective-C files such as this one.
-// Undefine these macros here, after everything has been #included, since
-// there will be no C++ uses and only Objective-C uses from this point on.
-#undef try
-#undef catch
-
-namespace {
-
-// Whether to allow NSExceptions to be raised on the current thread.
-LazyInstance<ThreadLocalBoolean>::Leaky
-    g_exceptionsAllowed = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-namespace base {
-namespace mac {
-
-bool GetNSExceptionsAllowed() {
-  return g_exceptionsAllowed.Get().Get();
-}
-
-void SetNSExceptionsAllowed(bool allowed) {
-  return g_exceptionsAllowed.Get().Set(allowed);
-}
-
-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);
-}
-
-ScopedNSExceptionEnabler::~ScopedNSExceptionEnabler() {
-  SetNSExceptionsAllowed(was_enabled_);
-}
-
-}  // namespace mac
-}  // namespace base
diff --git a/chrome/browser/chrome_browser_application_mac.mm b/chrome/browser/chrome_browser_application_mac.mm
index 02479c0..6d7c11c 100644
--- a/chrome/browser/chrome_browser_application_mac.mm
+++ b/chrome/browser/chrome_browser_application_mac.mm
@@ -12,7 +12,6 @@
 #include "base/debug/stack_trace.h"
 #import "base/logging.h"
 #include "base/mac/call_with_eh_frame.h"
-#import "base/mac/scoped_nsexception_enabler.h"
 #import "base/mac/scoped_nsobject.h"
 #import "base/mac/scoped_objc_class_swizzler.h"
 #import "base/metrics/histogram.h"
@@ -320,23 +319,8 @@ void CancelTerminate() {
       static_cast<long>(tag),
       [actionString UTF8String],
       aTarget);
-
   base::debug::ScopedCrashKey key(crash_keys::mac::kSendAction, value);
 
-  // Certain third-party code, such as print drivers, can still throw
-  // exceptions and Chromium cannot fix them.  This provides a way to
-  // work around those on a spot basis.
-  bool enableNSExceptions = false;
-
-  // http://crbug.com/80686 , an Epson printer driver.
-  if (anAction == @selector(selectPDE:)) {
-    enableNSExceptions = true;
-  }
-
-  // Minimize the window by keeping this close to the super call.
-  scoped_ptr<base::mac::ScopedNSExceptionEnabler> enabler;
-  if (enableNSExceptions)
-    enabler.reset(new base::mac::ScopedNSExceptionEnabler());
   return [super sendAction:anAction to:aTarget from:sender];
 }
 
diff --git a/chrome/browser/chrome_browser_application_mac_unittest.mm b/chrome/browser/chrome_browser_application_mac_unittest.mm
index 9c31806..7b2adc9 100644
--- a/chrome/browser/chrome_browser_application_mac_unittest.mm
+++ b/chrome/browser/chrome_browser_application_mac_unittest.mm
@@ -4,7 +4,6 @@
 
 #import <Cocoa/Cocoa.h>
 
-#import "base/mac/scoped_nsexception_enabler.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_samples.h"
@@ -20,8 +19,6 @@ namespace chrome_browser_application_mac {
 
 // Generate an NSException with the given name.
 NSException* ExceptionNamed(NSString* name) {
-  base::mac::ScopedNSExceptionEnabler enabler;
-
   return [NSException exceptionWithName:name
                                  reason:@"No reason given"
                                userInfo:nil];
diff --git a/chrome/browser/mac/keystone_glue.mm b/chrome/browser/mac/keystone_glue.mm
index f125fdfc..e1d2db5 100644
--- a/chrome/browser/mac/keystone_glue.mm
+++ b/chrome/browser/mac/keystone_glue.mm
@@ -18,7 +18,6 @@
 #include "base/mac/foundation_util.h"
 #include "base/mac/mac_logging.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
-#include "base/mac/scoped_nsexception_enabler.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/threading/worker_pool.h"
@@ -542,14 +541,7 @@ NSString* const kVersionKey = @"KSVersion";
   [self updateStatus:kAutoupdateRegistering version:nil];
 
   NSDictionary* parameters = [self keystoneParameters];
-  BOOL result;
-  {
-    // TODO(shess): Allows Keystone to throw an exception when
-    // /usr/bin/python does not exist (really!).
-    // http://crbug.com/86221 and http://crbug.com/87931
-    base::mac::ScopedNSExceptionEnabler enabler;
-    result = [registration_ registerWithParameters:parameters];
-  }
+  BOOL result = [registration_ registerWithParameters:parameters];
   if (!result) {
     [self updateStatus:kAutoupdateRegisterFailed version:nil];
     return;
diff --git a/chrome/browser/spellchecker/spellcheck_platform_mac.mm b/chrome/browser/spellchecker/spellcheck_platform_mac.mm
index 4e5061d..a22f829 100644
--- a/chrome/browser/spellchecker/spellcheck_platform_mac.mm
+++ b/chrome/browser/spellchecker/spellcheck_platform_mac.mm
@@ -12,7 +12,6 @@
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
-#include "base/mac/scoped_nsexception_enabler.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/time/time.h"
 #include "chrome/common/spellcheck_common.h"
@@ -36,10 +35,11 @@ const unsigned int kShortLanguageCodeSize = 2;
 // spell-checking will not work, but it also will not crash the
 // browser.
 NSSpellChecker* SharedSpellChecker() {
-  return base::mac::ObjCCastStrict<NSSpellChecker>(
-      base::mac::RunBlockIgnoringExceptions(^{
-          return [NSSpellChecker sharedSpellChecker];
-      }));
+  @try {
+    return [NSSpellChecker sharedSpellChecker];
+  } @catch (id exception) {
+    return nil;
+  }
 }
 
 // A private utility function to convert hunspell language codes to OS X
diff --git a/components/autofill/core/browser/personal_data_manager_mac.mm b/components/autofill/core/browser/personal_data_manager_mac.mm
index 1dcfbbc..5dfd5d7 100644
--- a/components/autofill/core/browser/personal_data_manager_mac.mm
+++ b/components/autofill/core/browser/personal_data_manager_mac.mm
@@ -11,7 +11,6 @@
 #include "base/format_macros.h"
 #include "base/guid.h"
 #include "base/logging.h"
-#import "base/mac/scoped_nsexception_enabler.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/metrics/histogram_macros.h"
@@ -122,10 +121,10 @@ ABAddressBook* GetAddressBook(PrefService* pref_service) {
   // +[ABAddressBook sharedAddressBook] throws an exception internally in
   // circumstances that aren't clear. The exceptions are only observed in crash
   // reports, so it is unknown whether they would be caught by AppKit and nil
-  // returned, or if they would take down the app. In either case, avoid
-  // crashing. http://crbug.com/129022
-  ABAddressBook* addressBook = base::mac::RunBlockIgnoringExceptions(
-      ^{ return [ABAddressBook sharedAddressBook]; });
+  // returned, or if they would take down the app.
+  // TODO(rsesek): If a crash is observed here, then the exception is not being
+  // caught by AppKit and it should be swallowed. http://crbug.com/129022
+  ABAddressBook* addressBook = [ABAddressBook sharedAddressBook];
   UMA_HISTOGRAM_BOOLEAN("Autofill.AddressBookAvailable", addressBook != nil);
 
   if (!g_accessed_address_book) {
diff --git a/media/capture/video/mac/video_capture_device_qtkit_mac.mm b/media/capture/video/mac/video_capture_device_qtkit_mac.mm
index 3415e03..2fc0b32 100644
--- a/media/capture/video/mac/video_capture_device_qtkit_mac.mm
+++ b/media/capture/video/mac/video_capture_device_qtkit_mac.mm
@@ -8,7 +8,6 @@
 
 #include "base/debug/crash_logging.h"
 #include "base/logging.h"
-#include "base/mac/scoped_nsexception_enabler.h"
 #include "media/base/video_capture_types.h"
 #include "media/capture/video/mac/video_capture_device_mac.h"
 #include "media/capture/video/video_capture_device.h"
@@ -19,13 +18,14 @@
 #pragma mark Class methods
 
 + (void)getDeviceNames:(NSMutableDictionary*)deviceNames {
-  // Third-party drivers often throw exceptions, which are fatal in
-  // Chromium (see comments in scoped_nsexception_enabler.h).  The
-  // following catches any exceptions and continues in an orderly
-  // fashion with no devices detected.
-  NSArray* captureDevices = base::mac::RunBlockIgnoringExceptions(^{
-    return [QTCaptureDevice inputDevicesWithMediaType:QTMediaTypeVideo];
-  });
+  // Third-party drivers often throw exceptions. The following catches any
+  // exceptions and continues in an orderly fashion with no devices detected.
+  NSArray* captureDevices = nil;
+  @try {
+    captureDevices =
+        [QTCaptureDevice inputDevicesWithMediaType:QTMediaTypeVideo];
+  } @catch (id exception) {
+  }
 
   for (QTCaptureDevice* device in captureDevices) {
     if ([[device attributeForKey:QTCaptureDeviceSuspendedAttribute] boolValue])
diff --git a/printing/printing_context_mac.mm b/printing/printing_context_mac.mm
index 8689897..36badc3 100644
--- a/printing/printing_context_mac.mm
+++ b/printing/printing_context_mac.mm
@@ -12,7 +12,6 @@
 #include "base/logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
-#include "base/mac/scoped_nsexception_enabler.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
@@ -86,11 +85,6 @@ void PrintingContextMac::AskUserForSettings(
     bool has_selection,
     bool is_scripted,
     const PrintSettingsCallback& callback) {
-  // Third-party print drivers seem to be an area prone to raising exceptions.
-  // This will allow exceptions to be raised, but does not handle them.  The
-  // NSPrintPanel appears to have appropriate NSException handlers.
-  base::mac::ScopedNSExceptionEnabler enabler;
-
   // Exceptions can also happen when the NSPrintPanel is being
   // deallocated, so it must be autoreleased within this scope.
   base::mac::ScopedNSAutoreleasePool pool;
diff --git a/ui/base/clipboard/clipboard_mac.mm b/ui/base/clipboard/clipboard_mac.mm
index e42a49f..6233194 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -11,7 +11,6 @@
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
-#import "base/mac/scoped_nsexception_enabler.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/stl_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ -307,9 +306,12 @@ SkBitmap ClipboardMac::ReadImage(ClipboardType type) const {
   // If the pasteboard's image data is not to its liking, the guts of NSImage
   // may throw, and that exception will leak. Prevent a crash in that case;
   // a blank image is better.
-  base::scoped_nsobject<NSImage> image(base::mac::RunBlockIgnoringExceptions(^{
-      return [[NSImage alloc] initWithPasteboard:GetPasteboard()];
-  }));
+  base::scoped_nsobject<NSImage> image;
+  @try {
+    image.reset([[NSImage alloc] initWithPasteboard:GetPasteboard()]);
+  } @catch (id exception) {
+  }
+
   SkBitmap bitmap;
   if (image.get()) {
     bitmap = gfx::NSImageToSkBitmapWithColorSpace(