Enable cpplint and fix cpplint errors in webrtc/api

Adding 'explicit' to these constructors has a low risk of causing
compatibility problems:
explicit RTCConfiguration(RTCConfigurationType type)
explicit IdBase(StatsType type)

BUG=webrtc:5267
TESTED=Fixed issues reported by:
find webrtc/api -type f -name *.cc -o -name *.h | xargs cpplint.py
followed by 'git cl presubmit'.

Review-Url: https://codereview.webrtc.org/2663063003
Cr-Commit-Position: refs/heads/master@{#16392}

PRESUBMIT.py

@@ -15,6 +15,7 @@ import sys
 
 # Directories that will be scanned by cpplint by the presubmit script.
 CPPLINT_DIRS = [
+  'webrtc/api',
   'webrtc/audio',
   'webrtc/call',
   'webrtc/common_video',

webrtc/api/datachannelinterface.h

@@ -75,7 +75,7 @@ class DataChannelObserver {
   //  A data buffer was successfully received.
   virtual void OnMessage(const DataBuffer& buffer) = 0;
   // The data channel's buffered_amount has changed.
-  virtual void OnBufferedAmountChange(uint64_t previous_amount){};
+  virtual void OnBufferedAmountChange(uint64_t previous_amount) {}
 
  protected:
   virtual ~DataChannelObserver() {}

webrtc/api/fakemetricsobserver.h

@@ -13,6 +13,7 @@
 
 #include <map>
 #include <string>
+#include <vector>
 
 #include "webrtc/api/peerconnectioninterface.h"
 #include "webrtc/base/thread_checker.h"

webrtc/api/jsepicecandidate.h

@@ -14,6 +14,8 @@
 #define WEBRTC_API_JSEPICECANDIDATE_H_
 
 #include <string>
+#include <utility>
+#include <vector>
 
 #include "webrtc/api/jsep.h"
 #include "webrtc/base/constructormagic.h"

webrtc/api/mediaconstraintsinterface.cc

@@ -70,7 +70,7 @@ void ConstraintToOptional(const webrtc::MediaConstraintsInterface* constraints,
     *value_out = rtc::Optional<T>(value);
   }
 }
-}
+}  // namespace
 
 namespace webrtc {
 

webrtc/api/mediastreamproxy.h

@@ -11,6 +11,8 @@
 #ifndef WEBRTC_API_MEDIASTREAMPROXY_H_
 #define WEBRTC_API_MEDIASTREAMPROXY_H_
 
+#include <string>
+
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/api/proxy.h"
 

webrtc/api/mediastreamtrackproxy.h

@@ -14,6 +14,8 @@
 #ifndef WEBRTC_API_MEDIASTREAMTRACKPROXY_H_
 #define WEBRTC_API_MEDIASTREAMTRACKPROXY_H_
 
+#include <string>
+
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/api/proxy.h"
 

webrtc/api/peerconnectioninterface.h

@@ -288,7 +288,7 @@ class PeerConnectionInterface : public rtc::RefCountInterface {
     // Chrome in particular.
 
     RTCConfiguration() = default;
-    RTCConfiguration(RTCConfigurationType type) {
+    explicit RTCConfiguration(RTCConfigurationType type) {
       if (type == RTCConfigurationType::kAggressive) {
         // These parameters are also defined in Java and IOS configurations,
         // so their values may be overwritten by the Java or IOS configuration.
@@ -669,7 +669,7 @@ class PeerConnectionObserver {
 
   // Triggered when a remote peer opens a data channel.
   virtual void OnDataChannel(
-      rtc::scoped_refptr<DataChannelInterface> data_channel){};
+      rtc::scoped_refptr<DataChannelInterface> data_channel) {}
   // Deprecated; please use the version that uses a scoped_refptr.
   virtual void OnDataChannel(DataChannelInterface* data_channel) {}
 

webrtc/api/peerconnectionproxy.h

@@ -11,6 +11,9 @@
 #ifndef WEBRTC_API_PEERCONNECTIONPROXY_H_
 #define WEBRTC_API_PEERCONNECTIONPROXY_H_
 
+#include <string>
+#include <vector>
+
 #include "webrtc/api/peerconnectioninterface.h"
 #include "webrtc/api/proxy.h"
 

webrtc/api/proxy.h

@@ -52,6 +52,7 @@
 #define WEBRTC_API_PROXY_H_
 
 #include <memory>
+#include <utility>
 
 #include "webrtc/base/event.h"
 #include "webrtc/base/thread.h"
@@ -349,6 +350,7 @@ class MethodCall5 : public rtc::Message,
   T5 a5_;
 };
 
+
 // Helper macros to reduce code duplication.
 #define PROXY_MAP_BOILERPLATE(c)                                \
   template <class INTERNAL_CLASS>                               \
@@ -363,6 +365,9 @@ class MethodCall5 : public rtc::Message,
     const INTERNAL_CLASS* internal() const { return c_.get(); } \
     INTERNAL_CLASS* internal() { return c_.get(); }
 
+#define END_PROXY_MAP() \
+  };
+
 #define SIGNALING_PROXY_MAP_BOILERPLATE(c)                               \
  protected:                                                              \
   c##ProxyWithInternal(rtc::Thread* signaling_thread, INTERNAL_CLASS* c) \
@@ -448,13 +453,13 @@ class MethodCall5 : public rtc::Message,
  private:                                                              \
   rtc::Thread* destructor_thread() const { return signaling_thread_; } \
                                                                        \
- public:
+ public:  // NOLINTNEXTLINE
 
 #define PROXY_WORKER_THREAD_DESTRUCTOR()                            \
  private:                                                           \
   rtc::Thread* destructor_thread() const { return worker_thread_; } \
                                                                     \
- public:
+ public:  // NOLINTNEXTLINE
 
 #define PROXY_METHOD0(r, method)                           \
   r method() override {                                    \
@@ -549,10 +554,6 @@ class MethodCall5 : public rtc::Message,
     return call.Marshal(RTC_FROM_HERE, worker_thread_);                      \
   }
 
-#define END_PROXY_MAP() \
-  }                     \
-  ;
-
 }  // namespace webrtc
 
 #endif  //  WEBRTC_API_PROXY_H_

webrtc/api/stats/rtcstats_objects.h

@@ -12,6 +12,7 @@
 #define WEBRTC_API_STATS_RTCSTATS_OBJECTS_H_
 
 #include <string>
+#include <vector>
 
 #include "webrtc/api/stats/rtcstats.h"
 

webrtc/api/statstypes.h

@@ -18,6 +18,7 @@
 #include <list>
 #include <map>
 #include <string>
+#include <vector>
 
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/constructormagic.h"
@@ -234,7 +235,7 @@ class StatsReport {
     // Protected since users of the IdBase type will be using the Id typedef.
     virtual bool Equals(const IdBase& other) const;
 
-    IdBase(StatsType type);  // Only meant for derived classes.
+    explicit IdBase(StatsType type);  // Only meant for derived classes.
     const StatsType type_;
 
     static const char kSeparator = '_';

webrtc/api/umametrics.h

@@ -113,7 +113,6 @@ enum IceCandidatePairType {
 
 class MetricsObserverInterface : public rtc::RefCountInterface {
  public:
-
   // |type| is the type of the enum counter to be incremented. |counter|
   // is the particular counter in that type. |counter_max| is the next sequence
   // number after the highest counter.