[cronet] make startNetLogToFile write to correct file

components/cronet/ios/Cronet.h

Index: components/cronet/ios/Cronet.h
diff --git a/components/cronet/ios/Cronet.h b/components/cronet/ios/Cronet.h
index d87f4a6848881c0311a9fc252ebfe086babea851..9d3598858976711fa296b62d635446fdb0f8083b 100644
--- a/components/cronet/ios/Cronet.h
+++ b/components/cronet/ios/Cronet.h
@@ -73,12 +73,12 @@ CRONET_EXPORT
 // This method must be called after |start|.
 + (void)installIntoSessionConfiguration:(NSURLSessionConfiguration*)config;
 
-// Starts net-internals logging to a file named |fileName| in the application
-// temporary directory. |fileName| must not be empty. Log level is determined
-// by |logBytes| - if YES then LOG_ALL otherwise LOG_ALL_BUT_BYTES. If the file
-// exists it is truncated before starting. If actively logging the call is
-// ignored.
-+ (void)startNetLogToFile:(NSString*)fileName logBytes:(BOOL)logBytes;
+// Starts net-internals logging to a file named |fileName|. If |fileName| is
+// relative, it puts it in the application home directory. |fileName| must not

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

Usually iOS documentation refers to 'documents' and 'temp' directory. These are
the directories where app has permissions to write to. I would assume that the
'home' directory is the root directory of the app where the app has no
permission. I think we should reference the documents directory here.

[lilyhoughton, 2016/11/22 20:48:42]

Done.

+// be empty. Log level is determined by |logBytes| - if YES then LOG_ALL
+// otherwise LOG_ALL_BUT_BYTES. If the file exists it is truncated before

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

It is not clear what LOG_ALL_BUT_BYTES mean here. Is it a constant defined
somewhere else?

[lilyhoughton, 2016/11/22 20:48:42]

It doesn't appear to refer to a constant used by the NetLog functions, and I'm
not familiar enough with the code that logBytes affects yet to know what it's
referring to.

+// starting. If actively logging the call is ignored.
++ (BOOL)startNetLogToFile:(NSString*)fileName logBytes:(BOOL)logBytes;
 
 // Stop net-internals logging and flush file to disk. If a logging session is
 // not in progress this call is ignored.