[wasm] Improve instrumentation for chrome://tracing

Currently, the tracing for background tasks is quite cryptic when
looking at chrome://tracing. Most tasks that are posted appear as
ThreadControllerImpl::RunTask, which when looking at other threads
can be deduced as compile tasks. Improve instrumentation to be more
indicative of the work being done.

BUG:v8:8423

Change-Id: I9b5469154ff7163d743efb1df998ca1df08cd4ce
Reviewed-on: https://chromium-review.googlesource.com/c/1330012
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57413}

src/wasm/module-compiler.cc

@@ -940,6 +940,8 @@ class BackgroundCompileTask : public CancelableTask {
 
   void RunInternal() override {
     TRACE_COMPILE("(3b) Compiling...\n");
+    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.wasm"),
+                 "BackgroundCompileTask::RunInternal");
     // The number of currently running background tasks is reduced in
     // {OnBackgroundTaskStopped}.
     CompilationEnv env = native_module_->CreateCompilationEnv();
@@ -2561,6 +2563,8 @@ class AsyncCompileJob::DecodeModule : public AsyncCompileJob::CompileStep {
       DisallowHeapAllocation no_allocation;
       // Decode the module bytes.
       TRACE_COMPILE("(1) Decoding module...\n");
+      TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.wasm"),
+                   "AsyncCompileJob::DecodeModule");
       result = DecodeWasmModule(
           job->enabled_features_, job->wire_bytes_.start(),
           job->wire_bytes_.end(), false, kWasmOrigin, counters_,

src/wasm/wasm-objects.cc

@@ -1044,6 +1044,7 @@ void WasmMemoryObject::RemoveInstance(Handle<WasmMemoryObject> memory,
 int32_t WasmMemoryObject::Grow(Isolate* isolate,
                                Handle<WasmMemoryObject> memory_object,
                                uint32_t pages) {
+  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.wasm"), "GrowMemory")
   Handle<JSArrayBuffer> old_buffer(memory_object->array_buffer(), isolate);
   if (!old_buffer->is_growable()) return -1;
   size_t old_size = old_buffer->byte_length();