camera: Hook PerfLogger to chrome://tracing

Bug: b/141518806
Test: Record for 'camera' category in chrome://tracing and launch CCA
Change-Id: I3240f8f88353ba446aaa3c70abfcda7db741337e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1928604
Commit-Queue: Wei Lee <wtlee@chromium.org>
Auto-Submit: Wei Lee <wtlee@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Shik Chen <shik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727351}

chrome/browser/resources/chromeos/camera/src/js/mojo/chrome_helper.js

@@ -34,6 +34,22 @@ export class ChromeHelper {
     });
   }
 
+  /**
+   * Triggers the begin of event tracing in Chrome.
+   * @param {string} event Name of the event.
+   */
+  startTracing(event) {
+    this.remote_.startPerfEventTrace(event);
+  }
+
+  /**
+   * Triggers the end of event tracing in Chrome.
+   * @param {string} event Name of the event.
+   */
+  stopTracing(event) {
+    this.remote_.stopPerfEventTrace(event);
+  }
+
   /**
    * Checks return value from |handleCameraResult|.
    * @param {string} caller Caller identifier.

chrome/browser/resources/chromeos/camera/src/js/perf.js

@@ -96,6 +96,7 @@ cca.perf.PerfLogger = class {
       return;
     }
     this.startTimeMap_.set(event, performance.now());
+    cca.mojo.ChromeHelper.getInstance().startTracing(event);
   }
 
   /**
@@ -126,6 +127,7 @@ cca.perf.PerfLogger = class {
     }
 
     const duration = performance.now() - startTime;
+    cca.mojo.ChromeHelper.getInstance().stopTracing(event);
     this.listeners_.forEach((listener) => listener(event, duration, perfInfo));
   }
 

components/chromeos_camera/camera_app_helper_impl.cc

@@ -5,6 +5,7 @@
 #include "components/chromeos_camera/camera_app_helper_impl.h"
 
 #include "ash/public/cpp/tablet_mode.h"
+#include "base/trace_event/trace_event.h"
 
 namespace chromeos_camera {
 
@@ -26,4 +27,12 @@ void CameraAppHelperImpl::IsTabletMode(IsTabletModeCallback callback) {
   std::move(callback).Run(ash::TabletMode::Get()->InTabletMode());
 }
 
+void CameraAppHelperImpl::StartPerfEventTrace(const std::string& event) {
+  TRACE_EVENT_BEGIN0("camera", event.c_str());
+}
+
+void CameraAppHelperImpl::StopPerfEventTrace(const std::string& event) {
+  TRACE_EVENT_END0("camera", event.c_str());
+}
+
 }  // namespace chromeos_camera

components/chromeos_camera/camera_app_helper_impl.h

@@ -28,6 +28,8 @@ class CameraAppHelperImpl : public chromeos_camera::mojom::CameraAppHelper {
                           const std::vector<uint8_t>& data,
                           HandleCameraResultCallback callback) override;
   void IsTabletMode(IsTabletModeCallback callback) override;
+  void StartPerfEventTrace(const std::string& event) override;
+  void StopPerfEventTrace(const std::string& event) override;
 
  private:
   CameraResultCallback camera_result_callback_;

components/chromeos_camera/common/camera_app_helper.mojom

@@ -20,4 +20,10 @@ interface CameraAppHelper {
 
   // Checks if device is under tablet mode currently.
   IsTabletMode() => (bool is_tablet_mode);
+
+  // Triggers the begin of event tracing for given |event|.
+  StartPerfEventTrace(string event);
+
+  // Triggers the end of event tracing for given |event|.
+  StopPerfEventTrace(string event);
 };