Increase the size of kVariationsKeySize.

This prevents triggering a NOTREACHED() for internal projects that have
a very large number of variations.

Bug: b:162438420
Change-Id: I171062c0d462e56f70cc6eb7ebeb279169279333
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2332571Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795684}

components/variations/BUILD.gn

@@ -2,12 +2,22 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/buildflag_header.gni")
+import("//build/config/chromecast_build.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
+large_variation_key_size_enabled =
+    is_chromecast
+
+buildflag_header("buildflags") {
+  header = "buildflags.h"
+  flags = [ "LARGE_VARIATION_KEY_SIZE=$large_variation_key_size_enabled" ]
+}
+
 static_library("variations") {
   sources = [
     "active_field_trials.cc",
@@ -73,6 +83,7 @@ static_library("variations") {
   }
 
   deps = [
+    ":buildflags",
     "proto",
     "//base",
     "//components/crash/core/common:crash_key",

components/variations/variations_crash_keys.cc

@@ -13,6 +13,7 @@
 #include "base/strings/stringprintf.h"
 #include "components/crash/core/common/crash_key.h"
 #include "components/variations/active_field_trials.h"
+#include "components/variations/buildflags.h"
 #include "components/variations/synthetic_trials.h"
 
 namespace variations {
@@ -22,7 +23,11 @@ namespace {
 // Size of the "num-experiments" crash key in bytes. 4096 bytes should be able
 // to hold about 227 entries, given each entry is 18 bytes long (due to being
 // of the form "8e7abfb0-c16397b7,").
+#if BUILDFLAG(LARGE_VARIATION_KEY_SIZE)
+constexpr size_t kVariationsKeySize = 8192;
+#else
 constexpr size_t kVariationsKeySize = 4096;
+#endif
 
 // Crash key reporting the number of experiments. 8 is the size of the crash key
 // in bytes, which is used to hold an int as a string.