[cronet] make startNetLogToFile write to correct file

components/cronet/ios/Cronet.mm

Index: components/cronet/ios/Cronet.mm
diff --git a/components/cronet/ios/Cronet.mm b/components/cronet/ios/Cronet.mm
index 150be2435ff32b9919574f60c8766995eb4f698b..66d6a97db63240bf05074be47d3836a302e71042 100644
--- a/components/cronet/ios/Cronet.mm
+++ b/components/cronet/ios/Cronet.mm
@@ -233,10 +233,16 @@ class CronetHttpProtocolHandlerDelegate
   config.protocolClasses = @[ [CRNPauseableHTTPProtocolHandler class] ];
 }
 
-+ (void)startNetLogToFile:(NSString*)fileName logBytes:(BOOL)logBytes {
++ (bool)startNetLogToFile:(NSString*)fileName logBytes:(BOOL)logBytes {

[mef, 2016/11/10 17:09:48]

BOOL

[lilyhoughton, 2016/11/16 16:04:10]

Done.

   if (gChromeNet.Get().get() && [fileName length]) {

[kapishnikov, 2016/11/10 20:52:17]

I think it would be better if we did the validation first and return 'NO' if the
fileName is invalid. Thus, we would have less code inside the 'if' statement.

[lilyhoughton, 2016/11/16 16:04:10]

I wanted to keep the obj-c wrapper as thin as possible, and keep as much code as
possible in the cpp api.

(Right now though it does check filelength twice, and I think that should
change)

[kapishnikov, 2016/11/18 22:17:27]

Acknowledged.

-    gChromeNet.Get()->StartNetLog([fileName UTF8String], logBytes);
+    NSURL* file =
+        [[[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory
+                                                 inDomains:NSUserDomainMask]
+            lastObject] URLByAppendingPathComponent:fileName];
+    return gChromeNet.Get()->StartNetLog(base::SysNSStringToUTF8([file path]), logBytes);
   }
+
+  return false;

[kapishnikov, 2016/11/10 20:52:17]

Use 'NO' instead of 'false' since it is Objective C.

[lilyhoughton, 2016/11/16 16:04:10]

Done.

 }
 
 + (void)stopNetLog {