Truncate the Javascript alert message if the length is too long on Mac port

chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm

Index: chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm b/chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm
index 7341835b372e3527306b29bcf4a07474317b3d93..40eabaaaf37c40eec31ffad74aea1f26d5846477 100644
--- a/chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm
+++ b/chrome/browser/ui/cocoa/javascript_app_modal_dialog_cocoa.mm
@@ -17,6 +17,8 @@
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/ui_base_types.h"
 
+const int kMessageTextMaxRows = 32;

[jeremy, 2014/01/21 21:24:39]

This is a cross-platform limit right, WDYT about using one constant across
platforms?

+
 // Helper object that receives the notification that the dialog/sheet is
 // going away. Is responsible for cleaning itself up.
 @interface JavaScriptAppModalDialogHelper : NSObject<NSAlertDelegate> {
@@ -146,6 +148,16 @@ JavaScriptAppModalDialogCocoa::JavaScriptAppModalDialogCocoa(
   [alert_ setDelegate:helper_];
   NSString* informative_text =
       base::SysUTF16ToNSString(dialog_->message_text());
+
+  NSArray * informative_text_array =

[jeremy, 2014/01/21 21:24:39]

Add a comment with a link to the bug - something like:
// Truncate long JS alerts - crbug.com/331219

+      [informative_text componentsSeparatedByCharactersInSet:
+          [NSCharacterSet newlineCharacterSet]];
+  if ([informative_text_array count] > kMessageTextMaxRows) {
+      informative_text = [[[[informative_text_array subarrayWithRange:
+          NSMakeRange(0, kMessageTextMaxRows)] valueForKey:@"description"]
+          componentsJoinedByString:@"\n"] stringByAppendingString:@"\n..."];

[jeremy, 2014/01/21 21:24:39]

Can you split this up into 3 or 4 statements so this is a little more readable?

+  }
+
   [alert_ setInformativeText:informative_text];
   NSString* message_text =
       base::SysUTF16ToNSString(dialog_->title());