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/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h b/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
index 3ce94ba..386989a 100644
--- a/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
+++ b/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
@@ -8,39 +8,4 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#import <Foundation/Foundation.h>
-
-#import <WebRTC/RTCMacros.h>
-
-/** The only valid value for the following if set is kRTCFieldTrialEnabledValue. */
-RTC_EXTERN NSString * const kRTCFieldTrialAudioSendSideBweKey;
-RTC_EXTERN NSString * const kRTCFieldTrialAudioSendSideBweForVideoKey;
-RTC_EXTERN NSString * const kRTCFieldTrialAudioForceNoTWCCKey;
-RTC_EXTERN NSString * const kRTCFieldTrialAudioForceABWENoTWCCKey;
-RTC_EXTERN NSString * const kRTCFieldTrialSendSideBweWithOverheadKey;
-RTC_EXTERN NSString * const kRTCFieldTrialFlexFec03AdvertisedKey;
-RTC_EXTERN NSString * const kRTCFieldTrialFlexFec03Key;
-RTC_EXTERN NSString * const kRTCFieldTrialImprovedBitrateEstimateKey;
-RTC_EXTERN NSString * const kRTCFieldTrialH264HighProfileKey;
-RTC_EXTERN NSString * const kRTCFieldTrialMinimizeResamplingOnMobileKey;
-
-/** The valid value for field trials above. */
-RTC_EXTERN NSString * const kRTCFieldTrialEnabledValue;
-
-/** Use a string returned by RTCFieldTrialMedianSlopeFilterValue as the value. */
-RTC_EXTERN NSString * const kRTCFieldTrialMedianSlopeFilterKey;
-RTC_EXTERN NSString *RTCFieldTrialMedianSlopeFilterValue(
-    size_t windowSize, double thresholdGain);
-
-/** Use a string returned by RTCFieldTrialTrendlineFilterValue as the value. */
-RTC_EXTERN NSString * const kRTCFieldTrialTrendlineFilterKey;
-/** Returns a valid value for kRTCFieldTrialTrendlineFilterKey. */
-RTC_EXTERN NSString *RTCFieldTrialTrendlineFilterValue(
-    size_t windowSize, double smoothingCoeff, double thresholdGain);
-
-/** Initialize field trials using a dictionary mapping field trial keys to their values. See above
- *  for valid keys and values.
- *  Must be called before any other call into WebRTC. See:
- *  webrtc/system_wrappers/include/field_trial_default.h
- */
-RTC_EXTERN void RTCInitFieldTrialDictionary(NSDictionary<NSString *, NSString *> *fieldTrials);
+#import "api/peerconnection/RTCFieldTrials.h"