I've reproduced this locally, and can confirm that reverting https://chromium.googlesource.com/chromium/src/+/5ef6e5486091988a425032ef49fce9dc3d78c3f1 fixes the problem (it removes the crashin test). 

I'll be happy to help figure this out, but in the meanwhile, could we revert https://chromium.googlesource.com/chromium/src/+/5ef6e5486091988a425032ef49fce9dc3d78c3f1 to unblock Cronet trybots?

For reland you can add the following line to CL description to run on Cronet trybots:

Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet

Thanks for looking into it! I'll just revert it now then.

It's already being reverted.

Great! So, the problem is that Cronet uses IDNStringUtil.java for IDN conversion on Android (to avoid ICU dependencies). 

This is controlled by 'use_platform_icu_alternatives' gn flag, which is set to 'true' in Cronet builds.

Adding "//url:url_java", to //net:net deps on android if use_platform_icu_alternatives is set fixes the issue:

diff --git a/net/BUILD.gn b/net/BUILD.gn
index dd99fa75984e..37f9b72ae152 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -2194,7 +2194,10 @@ component("net") {
       if (is_android) {
         # Use ICU alternative on Android.
         sources += [ "base/net_string_util_icu_alternatives_android.cc" ]
-        deps += [ ":net_jni_headers" ]
+        deps += [
+          ":net_jni_headers",
+          "//url:url_java",
+        ]

I would've expected that adding ":url_java" to public_deps of //url:url should have some effect, but for some reason it does NOT work:

diff --git a/url/BUILD.gn b/url/BUILD.gn
index d33801bc8ae8..2dcd015a6080 100644
--- a/url/BUILD.gn
+++ b/url/BUILD.gn
@@ -83,6 +83,7 @@ component("url") {
         "//base",
         "//base/third_party/dynamic_annotations",
       ]
+      public_deps = [ ":url_java" ]
     } else if (is_ios) {
       sources += [ "url_canon_icu_alternatives_ios.mm" ]
     } else {

I'm not quite sure what's going on, but I've played with it a little more and it appears that the following steps DO NOT fix the issue:

1. Adding //url:url_java to public_deps of //url:url
2. Adding //url:url_java to deps of //net:net
3. Adding //url:url to deps of //net:net
4. Adding //url:url to deps of //net:net_unittests

The following DOES fix the issue:

5. Adding //url:url_java to deps of //net:net_unittests

The CL with the fix that appears to work: https://chromium-review.googlesource.com/c/chromium/src/+/893681

I'm adding few folks who may know the explanation and suggest proper fix.

Java deps will only be noticed when they are added as deps to java targets. Add a *_java target as a dep to a native target (component / static_library / source_set) will cause the target to get compiled, but not to get included in the apk.

I think comment 7 explains it - //net:net is a "component", so its dependency on //url:url_java doesn't get noticed.

The //net:net_unittests is a "test" but does notice //url:url_java if it is added explicitly. The net_unittests target has explicit dependency on net_java: https://cs.chromium.org/chromium/src/net/BUILD.gn?l=5660 so it is consistent.

Does it mean that https://chromium-review.googlesource.com/c/chromium/src/+/893681 is a reasonable fix or should I remove "//url:url_java" from deps of //net:net as it is ignored anyway?

You should remove it from the component.

Otherwise fix lgtm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1722162ab0c760774720a2bbc3aa3b73d6b7db70

commit 1722162ab0c760774720a2bbc3aa3b73d6b7db70
Author: Misha Efimov <mef@chromium.org>
Date: Tue Jan 30 23:36:02 2018

Add //url:url_java to //net:net_unittests deps for Cronet Android builds.

Bug:  807283 
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ia61bdc85b5f700d58f88cc3093826d0a7e0ce014
Reviewed-on: https://chromium-review.googlesource.com/893681
Commit-Queue: Misha Efimov <mef@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533082}
[modify] https://crrev.com/1722162ab0c760774720a2bbc3aa3b73d6b7db70/net/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a54f0b52ea196f56565b6286f1d92689b27da50e

commit a54f0b52ea196f56565b6286f1d92689b27da50e
Author: Yixin Wang <wangyix@chromium.org>
Date: Wed Jan 31 05:43:18 2018

Reland x2 "Make PUSH_PROMISE headers URL-parsing more robust and conform to HTTP/2 spec"

net_unittest failure on android_cronet due to missing test app dependency should no longer occur after this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/893681

First reland: https://chromium-review.googlesource.com/c/chromium/src/+/891302
Original CL: https://chromium-review.googlesource.com/c/chromium/src/+/887970

Bug:807283

Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I622f074ad3d3ec89b78d754367285da52850e527
Reviewed-on: https://chromium-review.googlesource.com/893625
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Yixin Wang <wangyix@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533213}
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/BUILD.gn
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/chromium/quic_http_stream_test.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/quic_client_promised_info_test.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/quic_client_push_promise_index.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/quic_client_push_promise_index_test.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/quic_spdy_client_session_base.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/spdy_utils.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/spdy_utils.h
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/core/spdy_utils_test.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/platform/api/quic_url_utils.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/platform/api/quic_url_utils.h
[add] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/platform/api/quic_url_utils_test.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/platform/impl/quic_url_utils_impl.cc
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/quic/platform/impl/quic_url_utils_impl.h
[modify] https://crrev.com/a54f0b52ea196f56565b6286f1d92689b27da50e/net/tools/quic/quic_spdy_client_session_test.cc