[cpu-profiler] Lazily create CPU profiler.

We cannot drop the deprecated API right away because we need to keep binary compatiblity.
As a short term solution create CPU profiler lazily if the API is called.

BUG=v8:7070

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I04029844895976b25db165f4fba6afbfe1681913
Reviewed-on: https://chromium-review.googlesource.com/1047848Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53113}

src/api.cc

@@ -8016,7 +8016,7 @@ HeapProfiler* Isolate::GetHeapProfiler() {
 
 CpuProfiler* Isolate::GetCpuProfiler() {
   i::CpuProfiler* cpu_profiler =
-      reinterpret_cast<i::Isolate*>(this)->cpu_profiler();
+      reinterpret_cast<i::Isolate*>(this)->EnsureCpuProfiler();
   return reinterpret_cast<CpuProfiler*>(cpu_profiler);
 }
 

src/isolate.cc

@@ -2969,7 +2969,6 @@ bool Isolate::Init(StartupDeserializer* des) {
   date_cache_ = new DateCache();
   call_descriptor_data_ =
       new CallInterfaceDescriptorData[CallDescriptors::NUMBER_OF_DESCRIPTORS];
-  cpu_profiler_ = new CpuProfiler(this);
   heap_profiler_ = new HeapProfiler(heap());
   interpreter_ = new interpreter::Interpreter(this);
   compiler_dispatcher_ =
@@ -4065,6 +4064,13 @@ void Isolate::SetIdle(bool is_idle) {
   }
 }
 
+CpuProfiler* Isolate::EnsureCpuProfiler() {
+  if (!cpu_profiler_) {
+    cpu_profiler_ = new CpuProfiler(this);
+  }
+  return cpu_profiler_;
+}
+
 bool StackLimitCheck::JsHasOverflowed(uintptr_t gap) const {
   StackGuard* stack_guard = isolate_->stack_guard();
 #ifdef USE_SIMULATOR

src/isolate.h

@@ -1495,7 +1495,7 @@ class Isolate : private HiddenFactory {
 
   // TODO(alph): Remove along with the deprecated GetCpuProfiler().
   friend v8::CpuProfiler* v8::Isolate::GetCpuProfiler();
-  CpuProfiler* cpu_profiler() const { return cpu_profiler_; }
+  CpuProfiler* EnsureCpuProfiler();
 
   base::Atomic32 id_;
   EntryStackItem* entry_stack_;