Rename ScopedTaskEnvironment::ExecutionMode

ScopedTaskEnvironment::ExecutionMode is becoming
ScopedTaskEnvironment::ThreadPoolExecutionMode

This CL was uploaded by git cl split.

R=dougarnett@chromium.org

Bug: 708584
Change-Id: I834591a69bd1ffa8c87c73c7a890a92971b8f91d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583791
Auto-Submit: Carlos Caballero <carlscab@google.com>
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Commit-Queue: Carlos Caballero <carlscab@google.com>
Cr-Commit-Position: refs/heads/master@{#657418}

components/data_reduction_proxy/content/browser/data_reduction_proxy_pingback_client_impl_unittest.cc

@@ -111,7 +111,8 @@ class DataReductionProxyPingbackClientImplTest : public testing::Test {
   DataReductionProxyPingbackClientImplTest()
       : scoped_task_environment_(
             base::test::ScopedTaskEnvironment::MainThreadType::MOCK_TIME,
-            base::test::ScopedTaskEnvironment::ExecutionMode::ASYNC) {}
+            base::test::ScopedTaskEnvironment::ThreadPoolExecutionMode::ASYNC) {
+  }
 
   TestDataReductionProxyPingbackClientImpl* pingback_client() const {
     return pingback_client_.get();