Android: Add support for TraceEvent before the native library is loaded.

chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
index 92bcd1cb25f07012974916888267736947cd7034..8dc72fb0d3bcd8cc19b1421b719244329edcefe9 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
@@ -25,6 +25,7 @@ import org.chromium.base.ApplicationState;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ApplicationStatus.ApplicationStateListener;
 import org.chromium.base.BuildInfo;
+import org.chromium.base.CommandLine;
 import org.chromium.base.CommandLineInitUtil;
 import org.chromium.base.PathUtils;
 import org.chromium.base.ResourceExtractor;
@@ -203,6 +204,12 @@ public class ChromeApplication extends ContentApplication {
     @Override
     public void onCreate() {
         UmaUtils.recordMainEntryPointTime();
+        initCommandLine();
+        if (CommandLine.getInstance().hasSwitch("trace-startup")) {

[pasko, 2015/12/15 17:52:59]

This should also check for /data/local/chrome-trace-config.json.

I *think* we can speculatively start early tracing if the file exists and later
based on the contents decide whether we need the data.

Another option: do early tracing all the time, there are not too many events to
collect (yet).

See for details:
https://docs.google.com/document/d/1yRCXhrQ-0rsfUgNHt9T4YdnmJYrXKN6aK56Ozk3kP...

[Benoit L, 2016/01/06 12:50:06]

Done.

+            TraceEvent.enableEarlyTracing();
+        }
+        TraceEvent.begin("ChromeApplication.onCreate");
+
         super.onCreate();
         UiUtils.setKeyboardShowingDelegate(new UiUtils.KeyboardShowingDelegate() {
             @Override
@@ -238,6 +245,7 @@ public class ChromeApplication extends ContentApplication {
         // in the SyncController constructor.
         UniqueIdentificationGeneratorFactory.registerGenerator(SyncController.GENERATOR_ID,
                 new UuidBasedUniqueIdentificationGenerator(this, SESSIONS_UUID_PREF_KEY), false);
+        TraceEvent.end("ChromeApplication.onCreate");
     }
 
     /**