[Chromecast] Avoid BrowserMain for Android

Due to the recent change of
https://chromium-review.googlesource.com/c/chromium/src/+/1612248

Android specific logic inside of ContentMain is removed. Instead,
MainDelegate::RunProcess should return non negative number to avoid
BrowserMain to be called for Android.

Bug: None
Test: internal CQ
Change-Id: Iedb9f6940cc2f6b7e4cba563c52a6eb6e39e741d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637739Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Yuchen Liu <yucliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665293}

chromecast/app/cast_main_delegate.cc

@@ -180,7 +180,13 @@ int CastMainDelegate::RunProcess(
   // Note: Android must handle running its own browser process.
   // See ChromeMainDelegateAndroid::RunProcess.
   browser_runner_ = content::BrowserMainRunner::Create();
-  return browser_runner_->Initialize(main_function_params);
+  int exit_code = browser_runner_->Initialize(main_function_params);
+  // On Android we do not run BrowserMain(), so the above initialization of a
+  // BrowserMainRunner is all we want to occur. Return >= 0 to avoid running
+  // BrowserMain, while preserving any error codes > 0.
+  if (exit_code > 0)
+    return exit_code;
+  return 0;
 #else
   return -1;
 #endif  // defined(OS_ANDROID)