Replace the default timer task runner usages in tests

This is part of efforts to replace non-per-frame task runners with other
appropriate per-frame task runners in the renderer.

Bug: 804694
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ifcbf610a71e87f5570c3c0b5ffcda97fe10bfc39
Reviewed-on: https://chromium-review.googlesource.com/886441Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531868}

third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp

@@ -14,6 +14,7 @@
 #include "public/platform/Platform.h"
 #include "public/platform/WebScrollIntoViewParams.h"
 #include "public/platform/WebThread.h"
+#include "public/platform/scheduler/test/renderer_scheduler_test_support.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ -73,7 +74,7 @@ class ScrollableAreaStub : public GarbageCollectedFinalized<ScrollableAreaStub>,
   }
 
   scoped_refptr<WebTaskRunner> GetTimerTaskRunner() const final {
-    return Platform::Current()->CurrentThread()->Scheduler()->TimerTaskRunner();
+    return timer_task_runner_;
   }
 
   ScrollbarTheme& GetPageScrollbarTheme() const override {
@@ -89,7 +90,8 @@ class ScrollableAreaStub : public GarbageCollectedFinalized<ScrollableAreaStub>,
       : user_input_scrollable_x_(true),
         user_input_scrollable_y_(true),
         viewport_size_(viewport_size),
-        contents_size_(contents_size) {}
+        contents_size_(contents_size),
+        timer_task_runner_(blink::scheduler::CreateWebTaskRunnerForTesting()) {}
 
   CompositorElementId GetCompositorElementId() const override {
     return CompositorElementId();
@@ -131,6 +133,7 @@ class ScrollableAreaStub : public GarbageCollectedFinalized<ScrollableAreaStub>,
   ScrollOffset scroll_offset_;
   IntSize viewport_size_;
   IntSize contents_size_;
+  scoped_refptr<WebTaskRunner> timer_task_runner_;
 };
 
 class RootFrameViewStub : public ScrollableAreaStub {

third_party/WebKit/Source/platform/graphics/test/FakeScrollableArea.h

@@ -9,6 +9,7 @@
 #include "platform/scroll/ScrollableArea.h"
 #include "platform/scroll/ScrollbarThemeMock.h"
 #include "public/platform/Platform.h"
+#include "public/platform/scheduler/test/renderer_scheduler_test_support.h"
 
 namespace {
 blink::ScrollbarThemeMock scrollbar_theme_;
@@ -56,7 +57,10 @@ class FakeScrollableArea : public GarbageCollectedFinalized<FakeScrollableArea>,
   }
 
   scoped_refptr<WebTaskRunner> GetTimerTaskRunner() const final {
-    return Platform::Current()->CurrentThread()->Scheduler()->TimerTaskRunner();
+    if (!timer_task_runner_) {
+      timer_task_runner_ = blink::scheduler::CreateWebTaskRunnerForTesting();
+    }
+    return timer_task_runner_;
   }
 
   ScrollbarTheme& GetPageScrollbarTheme() const override {
@@ -69,6 +73,7 @@ class FakeScrollableArea : public GarbageCollectedFinalized<FakeScrollableArea>,
 
  private:
   ScrollOffset scroll_offset_;
+  mutable scoped_refptr<WebTaskRunner> timer_task_runner_;
 };
 
 }  // namespace blink

third_party/WebKit/Source/platform/scroll/ScrollAnimatorTest.cpp

@@ -35,6 +35,7 @@
 #include "platform/scroll/ScrollbarTheme.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebThread.h"
+#include "public/platform/scheduler/test/renderer_scheduler_test_support.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -119,7 +120,10 @@ class MockScrollableAreaForAnimatorTest
   }
 
   scoped_refptr<WebTaskRunner> GetTimerTaskRunner() const final {
-    return Platform::Current()->CurrentThread()->Scheduler()->TimerTaskRunner();
+    if (!timer_task_runner_) {
+      timer_task_runner_ = blink::scheduler::CreateWebTaskRunnerForTesting();
+    }
+    return timer_task_runner_;
   }
 
   ScrollbarTheme& GetPageScrollbarTheme() const override {
@@ -143,6 +147,7 @@ class MockScrollableAreaForAnimatorTest
   ScrollOffset min_offset_;
   ScrollOffset max_offset_;
   Member<ScrollAnimator> animator;
+  mutable scoped_refptr<WebTaskRunner> timer_task_runner_;
 };
 
 class TestScrollAnimator : public ScrollAnimator {