Obj-C SDK Cleanup

This CL separates the files under sdk/objc into logical directories, replacing
the previous file layout under Framework/.

A long term goal is to have some system set up to generate the files under
sdk/objc/api (the PeerConnection API wrappers) from the C++ code. In the shorter
term the goal is to abstract out shared concepts from these classes in order to
make them as uniform as possible.

The separation into base/, components/, and helpers/ are to differentiate between
the base layer's common protocols, various utilities and the actual platform
specific components.

The old directory layout that resembled a framework's internal layout is not
necessary, since it is generated by the framework target when building it.

Bug: webrtc:9627
Change-Id: Ib084fd83f050ae980649ca99e841f4fb0580bd8f
Reviewed-on: https://webrtc-review.googlesource.com/94142
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24493}
diff --git a/tools_webrtc/ios/generate_umbrella_header.py b/tools_webrtc/ios/generate_umbrella_header.py
index d8a87bf..3549735 100644
--- a/tools_webrtc/ios/generate_umbrella_header.py
+++ b/tools_webrtc/ios/generate_umbrella_header.py
@@ -8,7 +8,9 @@
 
 import argparse
 import datetime
+import os
 import sys
+import textwrap
 
 
 def GenerateUmbrellaHeader():
@@ -20,7 +22,8 @@
   args = parser.parse_args()
 
   with open(args.out, "w") as outfile:
-    outfile.write("""/*
+    outfile.write(textwrap.dedent("""\
+    /*
      *  Copyright %d The WebRTC project authors. All Rights Reserved.
      *
      *  Use of this source code is governed by a BSD-style license
@@ -28,10 +31,10 @@
      *  tree. An additional intellectual property rights grant can be found
      *  in the file PATENTS.  All contributing project authors may
      *  be found in the AUTHORS file in the root of the source tree.
-     */\n\n""" % datetime.datetime.now().year)
+     */\n\n""" % datetime.datetime.now().year))
 
     for s in args.sources:
-      outfile.write("#import <{}>\n".format(s))
+      outfile.write("#import <WebRTC/{}>\n".format(os.path.basename(s)))
 
   return 0