[M115][aw][tracing] Add a trace event tracking AwContents lifetime

This change adds a trace event with the 'android_webview.timeline'
category that starts in AwContents constructor and ends in AwContents
destructor.

(cherry picked from commit 876a1a3)

Bug: 1452205, b/280436352
Change-Id: Iec1133bf394cc15fe14d32cb5e543f54e579aba9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4573729
Reviewed-by: Alexander Timin <altimin@chromium.org>
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1153370}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4606043
Reviewed-by: Krishna Govind <govind@chromium.org>
Owners-Override: Krishna Govind <govind@chromium.org>
Cr-Commit-Position: refs/branch-heads/5790@{#704}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

android_webview/browser/aw_contents.cc

@@ -59,6 +59,8 @@
 #include "base/supports_user_data.h"
 #include "base/task/single_thread_task_runner.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/typed_macros.h"
 #include "components/android_autofill/browser/android_autofill_manager.h"
 #include "components/android_autofill/browser/autofill_provider_android.h"
 #include "components/autofill/content/browser/content_autofill_driver.h"
@@ -225,6 +227,8 @@ AwContents::AwContents(std::unique_ptr<WebContents> web_contents)
     : content::WebContentsObserver(web_contents.get()),
       browser_view_renderer_(this, content::GetUIThreadTaskRunner({})),
       web_contents_(std::move(web_contents)) {
+  TRACE_EVENT_BEGIN("android_webview.timeline", "WebView Instance",
+                    perfetto::Track::FromPointer(this));
   base::subtle::NoBarrier_AtomicIncrement(&g_instance_count, 1);
   icon_helper_ = std::make_unique<IconHelper>(web_contents_.get());
   icon_helper_->SetListener(this);
@@ -368,6 +372,9 @@ AwContents::~AwContents() {
   WebContentsObserver::Observe(nullptr);
   AwBrowserProcess::GetInstance()->visibility_metrics_logger()->RemoveClient(
       this);
+  // Corresponds to "WebView Instance" in AwContents's constructor.
+  TRACE_EVENT_END("android_webview.timeline",
+                  perfetto::Track::FromPointer(this));
 }
 
 base::android::ScopedJavaLocalRef<jobject> AwContents::GetWebContents(