webview: remove obsolete data dir lock metrics.

The retry behaviour of the WebView data directory lock is now
well-understood and we're not going to change the code any further;
remove the retry count metric.

Also remove the metric logging when init has already been started
previously - this has shown that a very small number of apps are
actually hitting this case and only in a very tiny percentage of cases.
Just remove the metric and don't introduce any new check for this
condition; these apps will either work or not and it's not worth us
worrying about it.

Fixed: 1142488
Change-Id: I90b85e999ca74ebecdc66c2ac7e11aa4b0bf1d2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2498110
Auto-Submit: Richard Coles <torne@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823305}

android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java

@@ -104,9 +104,6 @@ public class WebViewChromiumFactoryProvider implements WebViewFactoryProvider {
     private static WebViewChromiumFactoryProvider sSingleton;
     // Used to indicate if WebLayer and WebView are running in the same process.
     private static boolean sWebLayerRunningInSameProcess;
-    // Used to detect if we enter initialization for a second time, e.g. because an app caught and
-    // discarded an exception thrown by a previous failed initialization attempt.
-    private static volatile boolean sInitAlreadyStarted;
 
     private final WebViewChromiumRunQueue mRunQueue = new WebViewChromiumRunQueue(
             () -> { return WebViewChromiumFactoryProvider.this.mAwInit.hasStarted(); });
@@ -248,10 +245,6 @@ public class WebViewChromiumFactoryProvider implements WebViewFactoryProvider {
         long startTime = SystemClock.elapsedRealtime();
         try (ScopedSysTraceEvent e1 =
                         ScopedSysTraceEvent.scoped("WebViewChromiumFactoryProvider.initialize")) {
-            RecordHistogram.recordBooleanHistogram(
-                    "Android.WebView.Startup.InitAlreadyStarted", sInitAlreadyStarted);
-            sInitAlreadyStarted = true;
-
             PackageInfo packageInfo;
             try (ScopedSysTraceEvent e2 = ScopedSysTraceEvent.scoped(
                          "WebViewChromiumFactoryProvider.getLoadedPackageInfo")) {

android_webview/java/src/org/chromium/android_webview/AwDataDirLock.java

@@ -15,7 +15,6 @@ import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.PathUtils;
 import org.chromium.base.StrictModeContext;
-import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.ScopedSysTraceEvent;
 
 import java.io.File;
@@ -86,7 +85,6 @@ abstract class AwDataDirLock {
                 if (sExclusiveFileLock != null) {
                     // We got the lock; write out info for debugging.
                     writeCurrentProcessInfo(sLockFile);
-                    recordLockAttempts(attempts);
                     return;
                 }
 
@@ -108,8 +106,6 @@ abstract class AwDataDirLock {
                 throw new RuntimeException(error);
             } else {
                 Log.w(TAG, error);
-                // Record an attempt count of 0 to indicate that we proceeded without the lock.
-                recordLockAttempts(0);
             }
         }
     }
@@ -126,14 +122,6 @@ abstract class AwDataDirLock {
         }
     }
 
-    private static void recordLockAttempts(int attempts) {
-        // We log values from [0, LOCK_RETRIES]. Histogram samples are expected to be [0, max).
-        // 0 just goes to the underflow bucket, so min=1 and max=LOCK_RETRIES+1.
-        // To get bucket width 1, buckets must be max-min+2
-        RecordHistogram.recordLinearCountHistogram("Android.WebView.Startup.DataDirLockAttempts",
-                attempts, 1, LOCK_RETRIES + 1, LOCK_RETRIES + 2);
-    }
-
     private static String getLockFailureReason(final RandomAccessFile file) {
         final StringBuilder error = new StringBuilder("Using WebView from more than one process at "
                 + "once with the same data directory is not supported. https://crbug.com/558377 "

tools/metrics/histograms/histograms_xml/android/histograms.xml

@@ -2652,6 +2652,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Android.WebView.Startup.DataDirLockAttempts" units="attempts"
     expires_after="2020-12-10">
+  <obsolete>
+    Removed 2020-10
+  </obsolete>
   <owner>torne@chromium.org</owner>
   <owner>src/android_webview/OWNERS</owner>
   <summary>
@@ -2663,6 +2666,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Android.WebView.Startup.InitAlreadyStarted" enum="Boolean"
     expires_after="2020-12-10">
+  <obsolete>
+    Removed 2020-10
+  </obsolete>
   <owner>torne@chromium.org</owner>
   <owner>src/android_webview/OWNERS</owner>
   <summary>