Android: Ban all usages of System#exit

Apart from the build/tooling/test/third-party directories listed in
suppressions.xml, every usage of System#exit must be explicit and have
the @SuppressWarnings annotation, preferably with a short explanation of
why it is necessary.

Added @SuppressWarnings for all existing usages.

Removed the System#exit call in ChromeApplication since we have no
visibility into how often the application replacing bug is hit. Throwing
an exception with a custom message will help us see its current impact.

Bug: 1000651
Change-Id: Ia48598b32e339efccb0ca1b55ef03068da505410
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1851770
Auto-Submit: Peter Wen <wnwen@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706426}

base/android/java/src/org/chromium/base/library_loader/LibraryLoader.java

@@ -403,9 +403,6 @@ public class LibraryLoader {
 
             mLoaded = true;
         } catch (UnsatisfiedLinkError e) {
-            // Callers typically call System.exit() when catching this exception, make sure that it
-            // doesn't get lost.
-            Log.e(TAG, "Unable to load library.", e);
             throw new ProcessInitException(LoaderErrors.LOADER_ERROR_NATIVE_LIBRARY_LOAD_FAILED, e);
         }
     }

base/android/java/src/org/chromium/base/process_launcher/ChildProcessService.java

@@ -272,6 +272,7 @@ public class ChildProcessService {
         mMainThread.start();
     }
 
+    @SuppressWarnings("checkstyle:SystemExitCheck") // Allowed due to http://crbug.com/928521#c16.
     public void onDestroy() {
         Log.i(TAG, "Destroying ChildProcessService pid=%d", Process.myPid());
         System.exit(0);

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

@@ -19,7 +19,6 @@ import org.chromium.base.BuildInfo;
 import org.chromium.base.CommandLineInitUtil;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.JNIUtils;
-import org.chromium.base.Log;
 import org.chromium.base.PathUtils;
 import org.chromium.base.TraceEvent;
 import org.chromium.base.annotations.MainDex;
@@ -54,7 +53,6 @@ import org.chromium.ui.base.ResourceBundle;
  */
 public class ChromeApplication extends Application {
     private static final String COMMAND_LINE_FILE = "chrome-command-line";
-    private static final String TAG = "ChromiumApplication";
     // Public to allow use in ChromeBackupAgent
     public static final String PRIVATE_DATA_DIRECTORY_SUFFIX = "chrome";
 
@@ -170,8 +168,7 @@ public class ChromeApplication extends Application {
         // out-of-date application. Kill old applications in this bad state. See
         // http://crbug.com/658130 for more context and http://b.android.com/56296 for the bug.
         if (ContextUtils.getApplicationAssets() == null) {
-            Log.e(TAG, "getResources() null, closing app.");
-            System.exit(0);
+            throw new RuntimeException("App out of date, getResources() null, closing app.");
         }
     }
 

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

@@ -395,6 +395,7 @@ public class LaunchIntentDispatcher implements IntentHandler.IntentHandlerDelega
      * Handles launching a {@link ChromeTabbedActivity}.
      */
     @SuppressLint("InlinedApi")
+    @SuppressWarnings("checkstyle:SystemExitCheck") // Allowed due to https://crbug.com/847921#c17.
     private @Action int dispatchToTabbedActivity() {
         if (mIsVrIntent) {
             for (Activity activity : ApplicationStatus.getRunningActivities()) {

content/shell/android/shell_apk/src/org/chromium/content_shell_apk/ChildProcessLauncherTestHelperService.java

@@ -36,6 +36,7 @@ public class ChildProcessLauncherTestHelperService extends Service {
 
     private final Handler.Callback mHandlerCallback = new Handler.Callback() {
         @Override
+        @SuppressWarnings("checkstyle:SystemExitCheck") // Allowed due to ChildProcessService.
         public boolean handleMessage(Message msg) {
             switch (msg.what) {
                 case MSG_BIND_SERVICE:

tools/android/checkstyle/chromium-style-5.0.xml

@@ -145,11 +145,12 @@
       <property name="message" value="Please name the StrictModeContext variable &quot;ignored&quot; (crbug.com/767058#c4)."/>
     </module>
     <module name="RegexpSinglelineJava">
+      <!-- Tests are also allowed to use System.exit if need be, please add dirs to tools/android/checkstyle/suppressions.xml -->
       <property name="id" value="SystemExitCheck"/>
       <property name="severity" value="error"/>
-      <property name="format" value="System\.exit\([^0]"/>
+      <property name="format" value="System\.exit\("/>
       <property name="ignoreComments" value="true"/>
-      <property name="message" value="Throw an exception instead of calling System#exit with a non-zero exit status (crbug.com/1000651)."/>
+      <property name="message" value="Throw an exception instead of calling System#exit (crbug.com/1000651)."/>
     </module>
   </module>
 </module>

tools/android/checkstyle/suppressions.xml

@@ -15,6 +15,6 @@
   <suppress id="MethodNameCheck" files="FirstRunIntegrationUnitTest.java"/>
   <suppress id="MethodNameCheck" files="SplashActivityTest.java"/>
   <!-- Third-party libraries, test infrastructure, build, and tooling can use
-       System#exit freely. -->
-  <suppress id="SystemExitCheck" files="src/(build|testing|third_party|tools)/"/>
+       System#exit freely. Feel free to add other test directories here. -->
+  <suppress id="SystemExitCheck" files="src/(build|testing|third_party|tools|base/test)/"/>
 </suppressions>