UMA: clean imports for ChromeStabilityMetricsProvider

No change to logic, this just removes redundant imports to clarify this
class's dependencies.

Bug: 994839
Test: autoninja -C out/Default chrome
Change-Id: I579d9f1b3b24135fa729af3ca063eb3023a2d83e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1828497Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700917}

chrome/browser/metrics/chrome_stability_metrics_provider.cc

@@ -7,14 +7,12 @@
 #include <vector>
 
 #include "base/logging.h"
-#include "base/metrics/histogram_macros.h"
-#include "base/metrics/sparse_histogram.h"
 #include "build/build_config.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "content/public/browser/browser_child_process_observer.h"
 #include "content/public/browser/child_process_data.h"
 #include "content/public/browser/child_process_termination_info.h"
 #include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/process_type.h"
 #include "extensions/buildflags/buildflags.h"

chrome/browser/metrics/chrome_stability_metrics_provider.h

@@ -7,7 +7,6 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
-#include "base/process/kill.h"
 #include "base/scoped_observer.h"
 #include "build/build_config.h"
 #include "components/metrics/metrics_provider.h"