[Mac] Ignore spell-checker exceptions.

chrome/browser/spellchecker/spellchecker_mac.mm

Index: chrome/browser/spellchecker/spellchecker_mac.mm
diff --git a/chrome/browser/spellchecker/spellchecker_mac.mm b/chrome/browser/spellchecker/spellchecker_mac.mm
index 2f4f57abdf782c0054f23a3484324ddf5fc50e68..4c8484e1e8d47fd95bc4761d4cc4f22b976882f1 100644
--- a/chrome/browser/spellchecker/spellchecker_mac.mm
+++ b/chrome/browser/spellchecker/spellchecker_mac.mm
@@ -10,6 +10,8 @@
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
+#include "base/mac/foundation_util.h"
+#include "base/mac/scoped_nsexception_enabler.h"
 #include "base/metrics/histogram.h"
 #include "base/sys_string_conversions.h"
 #include "base/task.h"
@@ -27,6 +29,19 @@ namespace {
 // The number of characters in the first part of the language code.
 const unsigned int kShortLanguageCodeSize = 2;
 
+// +[NSSpellChecker sharedSpellChecker] can throw exceptions depending
+// on the state of the pasteboard, or possibly as a result of
+// third-party code (when setting up services entries).  The following
+// receives nil if an exception is thrown, in which case
+// spell-checking will not work, but it also will not crash the
+// browser.
+NSSpellChecker* SharedSpellChecker() {
+  return base::mac::ObjCCastStrict<NSSpellChecker>(
+      base::mac::PerformSelectorIgnoringExceptions(
+          [NSSpellChecker class],
+          @selector(sharedSpellChecker)));
+}

[Scott Hess - ex-Googler, 2011/12/09 01:46:28]

I don't _think_ it would be worth memo-izing this, but if you think it would be
worthwhile, that seems reasonable.  I also don't think it is worth histogramming
this, because as far as I can tell, there would be no action item.

+
 // TextCheckingTask is reserved for spell checking against large size
 // of text, which possible contains multiple paragrpahs.  Checking
 // that size of text might take time, and should be done as a task on
@@ -55,7 +70,7 @@ class TextCheckingTask : public Task {
     NSString* text_to_check = base::SysUTF16ToNSString(text_);
     size_t starting_at = 0;
     while (starting_at < text_.size()) {
-      NSRange range = [[NSSpellChecker sharedSpellChecker]
+      NSRange range = [SharedSpellChecker()
                          checkSpellingOfString:text_to_check
                                     startingAt:starting_at
                                       language:nil
@@ -152,8 +167,7 @@ std::string ConvertLanguageCodeFromMac(NSString* lang_code) {
 namespace SpellCheckerPlatform {
 
 void GetAvailableLanguages(std::vector<std::string>* spellcheck_languages) {
-  NSArray* availableLanguages = [[NSSpellChecker sharedSpellChecker]
-                        availableLanguages];
+  NSArray* availableLanguages = [SharedSpellChecker() availableLanguages];
   for (NSString* lang_code in availableLanguages) {
     spellcheck_languages->push_back(
               ConvertLanguageCodeFromMac(lang_code));
@@ -174,17 +188,17 @@ bool SpellCheckerProvidesPanel() {
 bool SpellingPanelVisible() {
   // This should only be called from the main thread.
   DCHECK([NSThread currentThread] == [NSThread mainThread]);
-  return [[[NSSpellChecker sharedSpellChecker] spellingPanel] isVisible];
+  return [[SharedSpellChecker() spellingPanel] isVisible];
 }
 
 void ShowSpellingPanel(bool show) {
   if (show) {
-    [[[NSSpellChecker sharedSpellChecker] spellingPanel]
+    [[SharedSpellChecker() spellingPanel]
         performSelectorOnMainThread:@selector(makeKeyAndOrderFront:)
                          withObject:nil
                       waitUntilDone:YES];
   } else {
-    [[[NSSpellChecker sharedSpellChecker] spellingPanel]
+    [[SharedSpellChecker() spellingPanel]
         performSelectorOnMainThread:@selector(close)
                          withObject:nil
                       waitUntilDone:YES];
@@ -193,7 +207,7 @@ void ShowSpellingPanel(bool show) {
 
 void UpdateSpellingPanelWithMisspelledWord(const string16& word) {
   NSString * word_to_display = base::SysUTF16ToNSString(word);
-  [[NSSpellChecker sharedSpellChecker]
+  [SharedSpellChecker()
       performSelectorOnMainThread:
         @selector(updateSpellingPanelWithMisspelledWord:)
                        withObject:word_to_display
@@ -208,9 +222,7 @@ bool PlatformSupportsLanguage(const std::string& current_language) {
   NSString* mac_lang_code = ConvertLanguageCodeToMac(current_language);
 
   // Then grab the languages available.
-  NSArray* availableLanguages;
-  availableLanguages = [[NSSpellChecker sharedSpellChecker]
-                        availableLanguages];
+  NSArray* availableLanguages = [SharedSpellChecker() availableLanguages];
 
   // Return true if the given language is supported by OS X.
   return [availableLanguages containsObject:mac_lang_code];
@@ -218,7 +230,7 @@ bool PlatformSupportsLanguage(const std::string& current_language) {
 
 void SetLanguage(const std::string& lang_to_set) {
   NSString* NS_lang_to_set = ConvertLanguageCodeToMac(lang_to_set);
-  [[NSSpellChecker sharedSpellChecker] setLanguage:NS_lang_to_set];
+  [SharedSpellChecker() setLanguage:NS_lang_to_set];
 }
 
 static int last_seen_tag_;
@@ -226,14 +238,14 @@ static int last_seen_tag_;
 bool CheckSpelling(const string16& word_to_check, int tag) {

[Scott Hess - ex-Googler, 2011/12/09 01:46:28]

This function was a case where having SharedSpellChecker() return nil seems like
it does the wrong thing.  The length should be 0, so it says there is no
misspelled word, which is wrong.  OTOH, the only other option is to say all
words are misspelled, and I can't think of any reasonable way to message the
user about re-installing their OS or whatever...

   last_seen_tag_ = tag;
 
-  // [[NSSpellChecker sharedSpellChecker] checkSpellingOfString] returns an
-  // NSRange that we can look at to determine if a word is misspelled.
+  // -[NSSpellChecker checkSpellingOfString] returns an NSRange that
+  // we can look at to determine if a word is misspelled.
   NSRange spell_range = {0,0};
 
   // Convert the word to an NSString.
   NSString* NS_word_to_check = base::SysUTF16ToNSString(word_to_check);
   // Check the spelling, starting at the beginning of the word.
-  spell_range = [[NSSpellChecker sharedSpellChecker]
+  spell_range = [SharedSpellChecker()
                   checkSpellingOfString:NS_word_to_check startingAt:0
                   language:nil wrap:NO inSpellDocumentWithTag:tag
                   wordCount:NULL];
@@ -249,8 +261,7 @@ void FillSuggestionList(const string16& wrong_word,
   NSString* NS_wrong_word = base::SysUTF16ToNSString(wrong_word);
   TimeTicks debug_begin_time = base::Histogram::DebugNow();
   // The suggested words for |wrong_word|.
-  NSArray* guesses =
-      [[NSSpellChecker sharedSpellChecker] guessesForWord:NS_wrong_word];
+  NSArray* guesses = [SharedSpellChecker() guessesForWord:NS_wrong_word];
   DHISTOGRAM_TIMES("Spellcheck.SuggestTime",
                    base::Histogram::DebugNow() - debug_begin_time);
 
@@ -264,12 +275,12 @@ void FillSuggestionList(const string16& wrong_word,
 
 void AddWord(const string16& word) {
     NSString* word_to_add = base::SysUTF16ToNSString(word);
-  [[NSSpellChecker sharedSpellChecker] learnWord:word_to_add];
+  [SharedSpellChecker() learnWord:word_to_add];
 }
 
 void RemoveWord(const string16& word) {
   NSString *word_to_remove = base::SysUTF16ToNSString(word);
-  [[NSSpellChecker sharedSpellChecker] unlearnWord:word_to_remove];
+  [SharedSpellChecker() unlearnWord:word_to_remove];
 }
 
 int GetDocumentTag() {
@@ -278,13 +289,12 @@ int GetDocumentTag() {
 }
 
 void IgnoreWord(const string16& word) {
-  [[NSSpellChecker sharedSpellChecker] ignoreWord:base::SysUTF16ToNSString(word)
-                           inSpellDocumentWithTag:last_seen_tag_];
+  [SharedSpellChecker() ignoreWord:base::SysUTF16ToNSString(word)
+            inSpellDocumentWithTag:last_seen_tag_];
 }
 
 void CloseDocumentWithTag(int tag) {
-  [[NSSpellChecker sharedSpellChecker]
-    closeSpellDocumentWithTag:static_cast<NSInteger>(tag)];
+  [SharedSpellChecker() closeSpellDocumentWithTag:static_cast<NSInteger>(tag)];
 }
 
 void RequestTextCheck(int route_id,