webview: remove ActualUiThread metric.

Remove the Android.WebView.ActualUiThread metric. The data shows the case where the UI thread decision is deferred is extremely rare, and when it is, it's virtually always ultimately the main looper. There's no need to keep collecting it. Fixed: 1178535 Bug: 1106486 Change-Id: Id71246a80134cb43bcb3797bee1294e05ef4950f Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2698988 Reviewed-by: Mark Pearson <[email protected]> Reviewed-by: Anna Malova <[email protected]> Commit-Queue: Richard Coles <[email protected]> Cr-Commit-Position: refs/heads/master@{#855767}
AryanGitHub · Feb 19, 2021 · 67f257d · 67f257d
1 parent 043eddd
commit 67f257d
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Showing 4 changed files with 6 additions and 50 deletions.
diff --git a/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromium.java b/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromium.java
@@ -305,10 +305,6 @@ public void init(final Map<String, Object> javaScriptInterfaces,
             } else if (!mFactory.hasStarted()) {
                 if (Looper.myLooper() == Looper.getMainLooper()) {
                     mFactory.startYourEngines(true);
-                } else {
-                    // Record which thread we're on now so we can track whether the final UI thread
-                    // decision differed.
-                    mFactory.getAwInit().setFirstWebViewConstructedOn(Looper.myLooper());
                 }
             }
 

diff --git a/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumAwInit.java b/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumAwInit.java
@@ -16,8 +16,6 @@
 import android.webkit.WebStorage;
 import android.webkit.WebViewDatabase;
 
-import androidx.annotation.IntDef;
-
 import org.chromium.android_webview.AwBrowserContext;
 import org.chromium.android_webview.AwBrowserProcess;
 import org.chromium.android_webview.AwContents;
@@ -94,7 +92,6 @@ public class WebViewChromiumAwInit {
     private static final int INIT_FINISHED = 2;
     // Read/write protected by mLock
     private int mInitState;
-    private Looper mFirstWebViewConstructedOn;
 
     private final WebViewChromiumFactoryProvider mFactory;
 
@@ -249,32 +246,6 @@ private void setUpResources(int packageId, Context context) {
         }
     }
 
-    // Only called for apps which target <JB MR2, and which construct WebView on a non-main thread.
-    void setFirstWebViewConstructedOn(Looper looper) {
-        synchronized (mLock) {
-            if (mInitState != INIT_FINISHED && mFirstWebViewConstructedOn == null) {
-                mFirstWebViewConstructedOn = looper;
-            }
-        }
-    }
-
-    // Used to record the UMA histogram Android.WebView.ActualUiThread. Since these values are
-    // persisted to logs, they should never be renumbered or reused.
-    @IntDef({ActualUiThread.FIRST_WEBVIEW_CONSTRUCTED, ActualUiThread.MAIN_LOOPER,
-            ActualUiThread.OTHER})
-    @interface ActualUiThread {
-        int FIRST_WEBVIEW_CONSTRUCTED = 0;
-        int MAIN_LOOPER = 1;
-        int OTHER = 2;
-
-        int COUNT = 3;
-    }
-
-    private static void recordActualUiThread(@ActualUiThread int value) {
-        RecordHistogram.recordEnumeratedHistogram(
-                "Android.WebView.ActualUiThread", value, ActualUiThread.COUNT);
-    }
-
     boolean hasStarted() {
         return mInitState == INIT_FINISHED;
     }
@@ -347,23 +318,6 @@ private void setChromiumUiThreadLocked(boolean fromThreadSafeFunction) {
                         + (Looper.getMainLooper().equals(looper) ? "main" : "background")
                         + " looper " + looper);
         ThreadUtils.setUiThread(looper);
-
-        // For apps targeting <JBMR2 which aren't required to commit to a thread in
-        // WebViewChromium.init, record a metric stating which thread we picked.
-        if (mFirstWebViewConstructedOn != null) {
-            if (looper == mFirstWebViewConstructedOn) {
-                // Using the same thread that the first WebView was constructed on.
-                recordActualUiThread(ActualUiThread.FIRST_WEBVIEW_CONSTRUCTED);
-            } else if (looper == Looper.getMainLooper()) {
-                // Using the main looper.
-                recordActualUiThread(ActualUiThread.MAIN_LOOPER);
-            } else {
-                // Using some other thread.
-                recordActualUiThread(ActualUiThread.OTHER);
-            }
-            // Reset to null to avoid leaking the app's looper.
-            mFirstWebViewConstructedOn = null;
-        }
     }
 
     private void initPlatSupportLibrary() {

diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
@@ -2135,6 +2135,9 @@ Unknown properties are collapsed to zero. -->
 </enum>
 
 <enum name="AndroidWebViewActualUiThread">
+  <obsolete>
+    Removed 02/2020. The ActualUiThread metric has been removed.
+  </obsolete>
   <int value="0" label="The thread on which the first WebView was constructed"/>
   <int value="1" label="The main looper"/>
   <int value="2" label="Some other thread"/>

diff --git a/tools/metrics/histograms/histograms_xml/android/histograms.xml b/tools/metrics/histograms/histograms_xml/android/histograms.xml
@@ -2242,6 +2242,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Android.WebView.ActualUiThread"
     enum="AndroidWebViewActualUiThread" expires_after="2021-03-31">
+  <obsolete>
+    Removed Feb 2021; they virtually always use the main thread.
+  </obsolete>
   <owner>[email protected]</owner>
   <owner>src/android_webview/OWNERS</owner>
   <summary>