weblayer: only read command line flags in debug builds

I believe the directory we're reading flags from is global, so
we should only attempt to do this in debug builds.

BUG=1034147
TEST=none

Change-Id: Ib7701bd12d900031470b13d73db5d88572b41e35
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1972210Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#725664}

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -56,7 +56,7 @@ public final class WebLayerImpl extends IWebLayer.Stub {
     // TODO: should there be one tag for all this code?
     private static final String TAG = "WebLayer";
     private static final String PRIVATE_DIRECTORY_SUFFIX = "weblayer";
-    // TODO: Configure this from the client.
+    // Command line flags are only read in debug builds.
     private static final String COMMAND_LINE_FILE = "/data/local/tmp/weblayer-command-line";
 
     private final ProfileManager mProfileManager = new ProfileManager();
@@ -158,11 +158,13 @@ public final class WebLayerImpl extends IWebLayer.Stub {
                 "org.chromium.weblayer.ChildProcessService$Sandboxed");
 
         if (!CommandLine.isInitialized()) {
-            // This disk read in the critical path is for development purposes only.
-            // TODO: Move it to debug-only (similar to WebView), or allow clients to configure the
-            // command line.
-            try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
-                CommandLine.initFromFile(COMMAND_LINE_FILE);
+            if (BuildInfo.isDebugAndroid()) {
+                // This disk read in the critical path is for development purposes only.
+                try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
+                    CommandLine.initFromFile(COMMAND_LINE_FILE);
+                }
+            } else {
+                CommandLine.init(null);
             }
         }