aw: Add more trace events to drawing functions

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index f8bd786b1515ae8729f4d43810ab0799e7f11cfb..5f4a20f9243d5cc353749ea7b540727d1887e6db 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -42,6 +42,7 @@ import org.chromium.android_webview.permission.AwPermissionRequest;
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.base.ThreadUtils;
+import org.chromium.base.TraceEvent;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.components.navigation_interception.InterceptNavigationDelegate;
 import org.chromium.components.navigation_interception.NavigationParams;
@@ -1050,7 +1051,12 @@ public class AwContents implements SmartClipProvider {
     //--------------------------------------------------------------------------------------------
 
     public void onDraw(Canvas canvas) {
-        mAwViewMethods.onDraw(canvas);
+        try {
+            TraceEvent.begin();
+            mAwViewMethods.onDraw(canvas);
+        } finally {
+            TraceEvent.end();
+        }
     }
 
     public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
@@ -2335,6 +2341,7 @@ public class AwContents implements SmartClipProvider {
         @Override
         public void onDraw(Canvas canvas) {
             if (isDestroyed()) {
+                TraceEvent.instant("EarlyOut_destroyed");
                 canvas.drawColor(getEffectiveBackgroundColor());
                 return;
             }
@@ -2342,6 +2349,7 @@ public class AwContents implements SmartClipProvider {
             // For hardware draws, the clip at onDraw time could be different
             // from the clip during DrawGL.
             if (!canvas.isHardwareAccelerated() && !canvas.getClipBounds(mClipBoundsTemporary)) {
+                TraceEvent.instant("EarlyOut_software_empty_clip");
                 return;
             }
 
@@ -2356,6 +2364,7 @@ public class AwContents implements SmartClipProvider {
                 did_draw = mNativeGLDelegate.requestDrawGL(canvas, false, mContainerView);
             }
             if (!did_draw) {
+                TraceEvent.instant("NativeDrawFailed");
                 canvas.drawColor(getEffectiveBackgroundColor());
             }