Use movable types for CallStackProfile(s) to remove copying of data.

components/metrics/call_stack_profile_metrics_provider.cc

Index: components/metrics/call_stack_profile_metrics_provider.cc
diff --git a/components/metrics/call_stack_profile_metrics_provider.cc b/components/metrics/call_stack_profile_metrics_provider.cc
index 3dc55b9ea6d00f0a571cd4bcbb528867f03f6a9f..9f323fdc28a48f2708826ddd768e1a8118dc8367 100644
--- a/components/metrics/call_stack_profile_metrics_provider.cc
+++ b/components/metrics/call_stack_profile_metrics_provider.cc
@@ -39,8 +39,10 @@ namespace {
 // with them.
 struct ProfilesState {
   ProfilesState(const CallStackProfileParams& params,
-                const base::StackSamplingProfiler::CallStackProfiles& profiles,
+                base::StackSamplingProfiler::CallStackProfiles profiles,
                 base::TimeTicks start_timestamp);
+  ProfilesState(ProfilesState&&);
+  ProfilesState& operator=(ProfilesState&&);
 
   // The metrics-related parameters provided to
   // CallStackProfileMetricsProvider::GetProfilerCallback().
@@ -54,16 +56,23 @@ struct ProfilesState {
   // via CallStackProfileMetricsProvider::GetProfilerCallback(). Used to
   // determine if collection was disabled during the collection of the profile.
   base::TimeTicks start_timestamp;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ProfilesState);
 };
 
 ProfilesState::ProfilesState(
     const CallStackProfileParams& params,
-    const base::StackSamplingProfiler::CallStackProfiles& profiles,
+    base::StackSamplingProfiler::CallStackProfiles profiles,
     base::TimeTicks start_timestamp)
     : params(params),
-      profiles(profiles),
-      start_timestamp(start_timestamp) {
-}
+      profiles(std::move(profiles)),
+      start_timestamp(start_timestamp) {}
+
+ProfilesState::ProfilesState(ProfilesState&&) = default;
+
+// Some versions of GCC need this for push_back to work with std::move.
+ProfilesState& ProfilesState::operator=(ProfilesState&&) = default;
 
 // PendingProfiles ------------------------------------------------------------
 
@@ -91,8 +100,9 @@ class PendingProfiles {
   // True if profiles are being collected.
   bool IsCollectionEnabled() const;
 
-  // Adds |profile| to the list of profiles if collection is enabled.
-  void CollectProfilesIfCollectionEnabled(const ProfilesState& profiles);
+  // Adds |profiles| to the list of profiles if collection is enabled; it is
+  // not const& because it must be passed with std::move.
+  void CollectProfilesIfCollectionEnabled(ProfilesState profiles);
 
   // Allows testing against the initial state multiple times.
   void ResetToDefaultStateForTesting();
@@ -153,7 +163,7 @@ bool PendingProfiles::IsCollectionEnabled() const {
 }
 
 void PendingProfiles::CollectProfilesIfCollectionEnabled(
-    const ProfilesState& profiles) {
+    ProfilesState profiles) {
   base::AutoLock scoped_lock(lock_);
 
   // Only collect if collection is not disabled and hasn't been disabled
@@ -164,7 +174,7 @@ void PendingProfiles::CollectProfilesIfCollectionEnabled(
     return;
   }
 
-  profiles_.push_back(profiles);
+  profiles_.push_back(std::move(profiles));
 }
 
 void PendingProfiles::ResetToDefaultStateForTesting() {
@@ -191,15 +201,14 @@ PendingProfiles::~PendingProfiles() {}
 void ReceiveCompletedProfilesImpl(
     const CallStackProfileParams& params,
     base::TimeTicks start_timestamp,
-    const StackSamplingProfiler::CallStackProfiles& profiles) {
+    StackSamplingProfiler::CallStackProfiles profiles) {
   PendingProfiles::GetInstance()->CollectProfilesIfCollectionEnabled(
-      ProfilesState(params, profiles, start_timestamp));
+      ProfilesState(params, std::move(profiles), start_timestamp));
 }
 
 // Invoked on an arbitrary thread. Ignores the provided profiles.
 void IgnoreCompletedProfiles(
-    const StackSamplingProfiler::CallStackProfiles& profiles) {
-}
+    StackSamplingProfiler::CallStackProfiles profiles) {}
 
 // Functions to encode protobufs ----------------------------------------------
 
@@ -398,8 +407,8 @@ CallStackProfileMetricsProvider::GetProfilerCallback(
 void CallStackProfileMetricsProvider::ReceiveCompletedProfiles(
     const CallStackProfileParams& params,
     base::TimeTicks start_timestamp,
-    const base::StackSamplingProfiler::CallStackProfiles& profiles) {
-  ReceiveCompletedProfilesImpl(params, start_timestamp, profiles);
+    base::StackSamplingProfiler::CallStackProfiles profiles) {
+  ReceiveCompletedProfilesImpl(params, start_timestamp, std::move(profiles));
 }
 
 void CallStackProfileMetricsProvider::OnRecordingEnabled() {