[aw] Add Finch experiments to Webview minidump

Add Finch Experiments info aka variations crash keys to Webview minidump. The keys are "variations" and "num-experiments".

Bug: 758450
Change-Id: Ib3bc7b872c0ff88eb404595496a9084f1d123ea9
Reviewed-on: https://chromium-review.googlesource.com/c/1305953
Commit-Queue: Hazem Ashmawy <hazems@chromium.org>
Reviewed-by: Tobias Sargeant <tobiasjs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604622}

android_webview/browser/aw_field_trial_creator.cc

@@ -25,6 +25,7 @@
 #include "components/prefs/pref_service_factory.h"
 #include "components/variations/entropy_provider.h"
 #include "components/variations/service/safe_seed_manager.h"
+#include "components/variations/variations_crash_keys.h"
 
 namespace android_webview {
 
@@ -78,6 +79,8 @@ void AwFieldTrialCreator::SetUpFieldTrials(PrefService* pref_service) {
       std::vector<std::string>(), /*low_entropy_provider=*/nullptr,
       std::make_unique<base::FeatureList>(), aw_field_trials_.get(),
       &ignored_safe_seed_manager);
+
+  variations::InitCrashKeys();
 }
 
 }  // namespace android_webview

android_webview/common/crash_reporter/crash_keys.cc

@@ -39,6 +39,18 @@ const char* const kWebViewCrashKeyWhiteList[] = {
     "mojo-message-error__3",
     "mojo-message-error__4",
     "total-discardable-memory-allocated",
+
+    // crash keys needed for recording finch trials
+    "variations",
+    "variations__1",
+    "variations__2",
+    "variations__3",
+    "variations__4",
+    "variations__5",
+    "variations__6",
+    "variations__7",
+    "variations__8",
+    "num-experiments",
     nullptr};
 // clang-format on