Add defaulted move constructors for some types that just got copy constructors

They can all benefit from moving, since they contain std::string and
std::vector. We intended to add these in
https://codereview.webrtc.org/1896953004/, but got compiler errors we
couldn't make sense of, so we skipped them. It turns out that what the
compiler was complaining about was that when we said we'd have a
user-defined move constructor, it stopped generating a copy assignment
operator for us. This CL solves the problem by outfitting the types
with defaulted copy and move assignment operators too.

Review URL: https://codereview.webrtc.org/1899173002

Cr-Commit-Position: refs/heads/master@{#12469}

webrtc/base/pathutils.cc

@@ -56,6 +56,7 @@ Pathname::Pathname()
 }
 
 Pathname::Pathname(const Pathname&) = default;
+Pathname::Pathname(Pathname&&) = default;
 
 Pathname::Pathname(const std::string& pathname)
     : folder_delimiter_(DEFAULT_FOLDER_DELIM) {
@@ -67,6 +68,9 @@ Pathname::Pathname(const std::string& folder, const std::string& filename)
   SetPathname(folder, filename);
 }
 
+Pathname& Pathname::operator=(const Pathname&) = default;
+Pathname& Pathname::operator=(Pathname&&) = default;
+
 void Pathname::SetFolderDelimiter(char delimiter) {
   ASSERT(IsFolderDelimiter(delimiter));
   folder_delimiter_ = delimiter;

webrtc/base/pathutils.h

@@ -45,9 +45,13 @@ public:
 
   Pathname();
   Pathname(const Pathname&);
+  Pathname(Pathname&&);
   Pathname(const std::string& pathname);
   Pathname(const std::string& folder, const std::string& filename);
 
+  Pathname& operator=(const Pathname&);
+  Pathname& operator=(Pathname&&);
+
   // Set's the default folder delimiter for this Pathname
   char folder_delimiter() const { return folder_delimiter_; }
   void SetFolderDelimiter(char delimiter);

webrtc/modules/audio_coding/codecs/audio_encoder.cc

@@ -16,10 +16,13 @@
 namespace webrtc {
 
 AudioEncoder::EncodedInfo::EncodedInfo() = default;
-
 AudioEncoder::EncodedInfo::EncodedInfo(const EncodedInfo&) = default;
-
+AudioEncoder::EncodedInfo::EncodedInfo(EncodedInfo&&) = default;
 AudioEncoder::EncodedInfo::~EncodedInfo() = default;
+AudioEncoder::EncodedInfo& AudioEncoder::EncodedInfo::operator=(
+    const EncodedInfo&) = default;
+AudioEncoder::EncodedInfo& AudioEncoder::EncodedInfo::operator=(EncodedInfo&&) =
+    default;
 
 int AudioEncoder::RtpTimestampRateHz() const {
   return SampleRateHz();

webrtc/modules/audio_coding/codecs/audio_encoder.h

@@ -46,7 +46,10 @@ class AudioEncoder {
   struct EncodedInfo : public EncodedInfoLeaf {
     EncodedInfo();
     EncodedInfo(const EncodedInfo&);
+    EncodedInfo(EncodedInfo&&);
     ~EncodedInfo();
+    EncodedInfo& operator=(const EncodedInfo&);
+    EncodedInfo& operator=(EncodedInfo&&);
 
     std::vector<EncodedInfoLeaf> redundant;
   };

webrtc/modules/desktop_capture/desktop_region.cc

@@ -21,6 +21,7 @@ DesktopRegion::RowSpan::RowSpan(int32_t left, int32_t right)
 }
 
 DesktopRegion::Row::Row(const Row&) = default;
+DesktopRegion::Row::Row(Row&&) = default;
 
 DesktopRegion::Row::Row(int32_t top, int32_t bottom)
     : top(top), bottom(bottom) {

webrtc/modules/desktop_capture/desktop_region.h

@@ -48,6 +48,7 @@ class DesktopRegion {
   // have the same vertical position.
   struct Row {
     Row(const Row&);
+    Row(Row&&);
     Row(int32_t top, int32_t bottom);
     ~Row();