[TaskScheduler]: Use ScopedBlockingCall to mark blocking tasks.

This CL uses ScopedBlockingCall to mark blocking calls in /chrome/browser/safe_browsing/incident_reporting.

This CL was created by replacing calls to AssertBlockingAllowed()
with instantiations of ScopedBlockingCall(MAY_BLOCK).
I kindly ask the reviewer to make sure of the following:
  - ScopedBlockingCall is instantiated in a scope with minimal CPU usage.
    If this is not the case, ScopedBlockingCall should be instantiated
    closer to the blocking call. See scoped_blocking_call.h for more
    info. Please let me know when/where the blocking call happens if this needs
    to be changed.
  - Parameter |blocking_type| matches expectation (MAY_BLOCK/WILL_BLOCK). See
    BlockingType for more info. While I assumed MAY_BLOCK by default, that might
    not be the best fit if we know that this callsite is guaranteed to block.
  - The ScopedBlockingCall's scope covers the entirety of the blocking operation
    previously asserted against by the AssertBlockingAllowed().

This CL was uploaded by git cl split.

R=proberge@chromium.org

Bug: 874080
Change-Id: I0aad6d7dd8dd315323a365f900b9074559bd0a7f
Reviewed-on: https://chromium-review.googlesource.com/1191192
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: proberge <proberge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586403}

chrome/browser/safe_browsing/incident_reporting/environment_data_collection.cc

@@ -8,7 +8,7 @@
 
 #include "base/cpu.h"
 #include "base/sys_info.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/threading/scoped_blocking_call.h"
 #include "build/build_config.h"
 #include "chrome/common/channel_info.h"
 #include "components/safe_browsing/proto/csd.pb.h"
@@ -64,7 +64,7 @@ void CollectProcessData(ClientIncidentReport_EnvironmentData_Process* process) {
 }  // namespace
 
 void CollectEnvironmentData(ClientIncidentReport_EnvironmentData* data) {
-  base::AssertBlockingAllowed();
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::WILL_BLOCK);
 
   // OS
   {