Android: Report fake crashes for DexFixer failures

UMA currently shows that:
  Os.stat() fails .14% of the time
  Runtime.exec() fails 0.02%

I suspect the heuristic for where the .odex files live might be wrong
for some small portion of devices, so would like to collect these
crashes.

Bug: 1152970
Change-Id: I98d1a14ae670bb1be04de6a4564001b65a67a1a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2624808Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842563}

chrome/android/java/src/org/chromium/chrome/browser/base/DexFixer.java

@@ -18,6 +18,7 @@ import dalvik.system.DexFile;
 import org.chromium.base.BuildConfig;
 import org.chromium.base.BuildInfo;
 import org.chromium.base.ContextUtils;
+import org.chromium.base.JavaExceptionReporter;
 import org.chromium.base.Log;
 import org.chromium.base.compat.ApiHelperForM;
 import org.chromium.base.compat.ApiHelperForO;
@@ -29,6 +30,7 @@ import org.chromium.chrome.browser.DeferredStartupHandler;
 import org.chromium.chrome.browser.preferences.ChromePreferenceKeys;
 import org.chromium.chrome.browser.preferences.SharedPreferencesManager;
 import org.chromium.chrome.browser.version.ChromeVersionInfo;
+import org.chromium.content_public.browser.UiThreadTaskTraits;
 
 import java.io.File;
 import java.io.IOException;
@@ -41,6 +43,12 @@ public class DexFixer {
     private static final String TAG = "DexFixer";
     private static boolean sHasIsolatedSplits;
 
+    private static class DexFixerException extends Exception {
+        DexFixerException(String reason, Throwable causedBy) {
+            super(reason, causedBy);
+        }
+    }
+
     @WorkerThread
     public static void fixDexInBackground() {
         if (shouldSkipDexFix()) {
@@ -77,16 +85,23 @@ public class DexFixer {
         int reason = needsDexCompile(appInfo);
         if (reason > DexFixerReason.NOT_NEEDED) {
             Log.w(TAG, "Triggering dex compile. Reason=%d", reason);
+            String cmd = "cmd package compile -r shared ";
+            if (reason == DexFixerReason.NOT_READABLE && BuildConfig.ISOLATED_SPLITS_ENABLED) {
+                // Isolated processes need only access the base split.
+                String apkBaseName = new File(appInfo.sourceDir).getName();
+                cmd += String.format("--split %s ", apkBaseName);
+            }
+            cmd += ContextUtils.getApplicationContext().getPackageName();
             try {
-                String cmd = "cmd package compile -r shared ";
-                if (reason == DexFixerReason.NOT_READABLE && BuildConfig.ISOLATED_SPLITS_ENABLED) {
-                    // Isolated processes need only access the base split.
-                    String apkBaseName = new File(appInfo.sourceDir).getName();
-                    cmd += String.format("--split %s ", apkBaseName);
-                }
-                cmd += ContextUtils.getApplicationContext().getPackageName();
                 runtime.exec(cmd);
             } catch (IOException e) {
+                DexFixerException dfException =
+                        new DexFixerException(String.format("Reason: %s Name: %s", reason,
+                                                      new File(appInfo.sourceDir).getName()),
+                                e);
+                // TODO(agrieve): Remove reportException() once some data is collected.
+                PostTask.postTask(UiThreadTaskTraits.BEST_EFFORT,
+                        () -> JavaExceptionReporter.reportException(dfException));
                 reason = DexFixerReason.FAILED_TO_RUN;
             }
         }
@@ -174,6 +189,11 @@ public class DexFixer {
                 return DexFixerReason.NOT_READABLE;
             }
         } catch (ErrnoException e) {
+            // TODO(agrieve): Remove reportException() once some data is collected.
+            DexFixerException dfException = new DexFixerException(
+                    String.format("Path: %s exists: %s", oatPath, new File(oatPath).exists()), e);
+            PostTask.postTask(UiThreadTaskTraits.BEST_EFFORT,
+                    () -> JavaExceptionReporter.reportException(dfException));
             return DexFixerReason.STAT_FAILED;
         }
         return DexFixerReason.NOT_NEEDED;