Remove flag for virtual-viewport pinch to zoom and old paths.

Virtual viewport has been shipping by default for a while now and the old
path is mostly removed in Blink so this flag doesn't do anything. There's
also some branching based on this flag that we can now remove. This patch
removes all dead code so it should have no effect.

BUG=304869
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1155063003

Cr-Commit-Position: refs/heads/master@{#331955}

35 files changed, 37 insertions, 175 deletions

diff --git a/android_webview/browser/hardware_renderer.h b/android_webview/browser/hardware_renderer.h
index 963b30b..f06501f 100644
--- a/android_webview/browser/hardware_renderer.h
+++ b/android_webview/browser/hardware_renderer.h
@@ -49,9 +49,6 @@ class HardwareRenderer : public cc::LayerTreeHostClient,
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override {}
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override {}
   void DidFailToInitializeOutputSurface() override;
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index 02a516a..b95ac11 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -48,10 +48,6 @@ const char kCompositeToMailbox[] = "composite-to-mailbox";
 const char kStrictLayerPropertyChangeChecking[] =
     "strict-layer-property-change-checking";
 
-// Virtual viewport for fixed-position elements, scrollbars during pinch.
-const char kEnablePinchVirtualViewport[] = "enable-pinch-virtual-viewport";
-const char kDisablePinchVirtualViewport[] = "disable-pinch-virtual-viewport";
-
 // Ensures that the draw properties computed via the property trees match those
 // computed by CalcDrawProperties.
 const char kEnablePropertyTreeVerification[] =
diff --git a/cc/base/switches.h b/cc/base/switches.h
index c7a809a..2d29341 100644
--- a/cc/base/switches.h
+++ b/cc/base/switches.h
@@ -26,8 +26,6 @@ CC_EXPORT extern const char kTopControlsShowThreshold[];
 CC_EXPORT extern const char kSlowDownRasterScaleFactor[];
 CC_EXPORT extern const char kCompositeToMailbox[];
 CC_EXPORT extern const char kMaxUnusedResourceMemoryUsagePercentage[];
-CC_EXPORT extern const char kEnablePinchVirtualViewport[];
-CC_EXPORT extern const char kDisablePinchVirtualViewport[];
 CC_EXPORT extern const char kStrictLayerPropertyChangeChecking[];
 CC_EXPORT extern const char kEnablePropertyTreeVerification[];
 
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 2c39865..65a7a50 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -405,12 +405,10 @@ void LayerImpl::GetContentsResourceId(ResourceId* resource_id,
 
 gfx::Vector2dF LayerImpl::ScrollBy(const gfx::Vector2dF& scroll) {
   gfx::ScrollOffset adjusted_scroll(scroll);
-  if (layer_tree_impl()->settings().use_pinch_virtual_viewport) {
-    if (!user_scrollable_horizontal_)
-      adjusted_scroll.set_x(0);
-    if (!user_scrollable_vertical_)
-      adjusted_scroll.set_y(0);
-  }
+  if (!user_scrollable_horizontal_)
+    adjusted_scroll.set_x(0);
+  if (!user_scrollable_vertical_)
+    adjusted_scroll.set_y(0);
   DCHECK(scrollable());
   gfx::ScrollOffset old_offset = CurrentScrollOffset();
   gfx::ScrollOffset new_offset =
@@ -649,27 +647,7 @@ gfx::Vector2dF LayerImpl::FixedContainerSizeDelta() const {
   // In virtual-viewport mode, we don't need to compensate for pinch zoom or
   // scale since the fixed container is the outer viewport, which sits below
   // the page scale.
-  if (layer_tree_impl()->settings().use_pinch_virtual_viewport)
-    return delta_from_scroll;
-
-  float scale_delta = layer_tree_impl()->page_scale_delta();
-  float scale = layer_tree_impl()->current_page_scale_factor() /
-                layer_tree_impl()->page_scale_delta();
-
-  delta_from_scroll.Scale(1.f / scale);
-
-  // The delta-from-pinch component requires some explanation: A viewport of
-  // size (w,h) will appear to be size (w/s,h/s) under scale s in the content
-  // space. If s -> s' on the impl thread, where s' = s * ds, then the apparent
-  // viewport size change in the content space due to ds is:
-  //
-  // (w/s',h/s') - (w/s,h/s) = (w,h)(1/s' - 1/s) = (w,h)(1 - ds)/(s ds)
-  //
-  gfx::Vector2dF delta_from_pinch =
-      gfx::Rect(scroll_clip_layer_->bounds()).bottom_right() - gfx::PointF();
-  delta_from_pinch.Scale((1.f - scale_delta) / (scale * scale_delta));
-
-  return delta_from_scroll + delta_from_pinch;
+  return delta_from_scroll;
 }
 
 base::DictionaryValue* LayerImpl::LayerTreeAsJson() const {
diff --git a/cc/layers/layer_impl_unittest.cc b/cc/layers/layer_impl_unittest.cc
index d9811bc..713a99d 100644
--- a/cc/layers/layer_impl_unittest.cc
+++ b/cc/layers/layer_impl_unittest.cc
@@ -458,7 +458,6 @@ class LayerImplScrollTest : public testing::Test {
 
   LayerTreeSettings settings() {
     LayerTreeSettings settings;
-    settings.use_pinch_virtual_viewport = true;
     return settings;
   }
 
@@ -682,7 +681,6 @@ class LayerImplScrollbarSyncTest : public testing::Test {
 
   LayerTreeSettings settings() {
     LayerTreeSettings settings;
-    settings.use_pinch_virtual_viewport = true;
     return settings;
   }
 
diff --git a/cc/test/fake_layer_tree_host_client.h b/cc/test/fake_layer_tree_host_client.h
index b5093ad..206ad29 100644
--- a/cc/test/fake_layer_tree_host_client.h
+++ b/cc/test/fake_layer_tree_host_client.h
@@ -40,10 +40,6 @@ class FakeLayerTreeHostClient : public LayerTreeHostClient,
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override {}
-
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override {}
   void DidFailToInitializeOutputSurface() override;
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index cac431f..20ea9c6 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -406,13 +406,6 @@ class LayerTreeHostClientForTesting : public LayerTreeHostClient,
                                      elastic_overscroll_delta, page_scale,
                                      top_controls_delta);
   }
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float scale,
-                           float top_controls_delta) override {
-    test_hooks_->ApplyViewportDeltas(scroll_delta,
-                                     scale,
-                                     top_controls_delta);
-  }
 
   void RequestNewOutputSurface() override {
     test_hooks_->RequestNewOutputSurface();
diff --git a/cc/test/layer_tree_test.h b/cc/test/layer_tree_test.h
index cbda75e..9b22a04 100644
--- a/cc/test/layer_tree_test.h
+++ b/cc/test/layer_tree_test.h
@@ -71,9 +71,6 @@ class TestHooks : public AnimationDelegate {
       const gfx::Vector2dF& elastic_overscroll_delta,
       float scale,
       float top_controls_delta) {}
-  virtual void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                                   float scale,
-                                   float top_controls_delta) {}
   virtual void BeginMainFrame(const BeginFrameArgs& args) {}
   virtual void WillBeginMainFrame() {}
   virtual void DidBeginMainFrame() {}
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index dd56420..21e2b7e 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -1072,22 +1072,12 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
 
     ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
     elastic_overscroll_ += info->elastic_overscroll_delta;
-    if (!settings_.use_pinch_virtual_viewport) {
-      // TODO(miletus): Make sure either this code path is totally gone,
-      // or revisit the flooring here if the old pinch viewport code path
-      // is causing problems with fractional scroll offset.
-      client_->ApplyViewportDeltas(
-          gfx::ToFlooredVector2d(inner_viewport_scroll_delta +
-                                 outer_viewport_scroll_delta),
-          info->page_scale_delta, info->top_controls_delta);
-    } else {
-      // TODO(ccameron): pass the elastic overscroll here so that input events
-      // may be translated appropriately.
-      client_->ApplyViewportDeltas(
-          inner_viewport_scroll_delta, outer_viewport_scroll_delta,
-          info->elastic_overscroll_delta, info->page_scale_delta,
-          info->top_controls_delta);
-    }
+    // TODO(ccameron): pass the elastic overscroll here so that input events
+    // may be translated appropriately.
+    client_->ApplyViewportDeltas(
+        inner_viewport_scroll_delta, outer_viewport_scroll_delta,
+        info->elastic_overscroll_delta, info->page_scale_delta,
+        info->top_controls_delta);
   }
 }
 
diff --git a/cc/trees/layer_tree_host_client.h b/cc/trees/layer_tree_host_client.h
index 6b30532..3aa041f 100644
--- a/cc/trees/layer_tree_host_client.h
+++ b/cc/trees/layer_tree_host_client.h
@@ -35,9 +35,6 @@ class LayerTreeHostClient {
       const gfx::Vector2dF& elastic_overscroll_delta,
       float page_scale,
       float top_controls_delta) = 0;
-  virtual void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                                   float page_scale,
-                                   float top_controls_delta) = 0;
   // Request an OutputSurface from the client. When the client has one it should
   // call LayerTreeHost::SetOutputSurface.  This will result in either
   // DidFailToInitializeOutputSurface or DidInitializeOutputSurface being
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 6377818..70d3b30 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -109,7 +109,6 @@ class LayerTreeHostImplTest : public testing::Test,
     settings.impl_side_painting = true;
     settings.renderer_settings.texture_id_allocation_chunk_size = 1;
     settings.report_overscroll_only_for_scrollable_axes = true;
-    settings.use_pinch_virtual_viewport = true;
     settings.gpu_rasterization_enabled = true;
     return settings;
   }
@@ -2531,8 +2530,6 @@ class LayerTreeHostImplTopControlsTest : public LayerTreeHostImplTest {
       : layer_size_(10, 10),
         clip_size_(layer_size_),
         top_controls_height_(50) {
-    settings_.use_pinch_virtual_viewport = true;
-
     viewport_size_ = gfx::Size(clip_size_.width(),
                                clip_size_.height() + top_controls_height_);
   }
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 6ea6b7f..53de149 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -1291,7 +1291,9 @@ class LayerTreeHostTestStartPageScaleAnimation : public LayerTreeHostTest {
 
   void BeginTest() override { PostSetNeedsCommitToMainThread(); }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& scroll_delta,
+                           const gfx::Vector2dF&,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float) override {
     gfx::ScrollOffset offset = scroll_layer_->scroll_offset();
@@ -6038,15 +6040,6 @@ class LayerTreeHostAcceptsDeltasFromImplWithoutRootLayer
     deltas_sent_to_client_ = true;
   }
 
-  void ApplyViewportDeltas(
-      const gfx::Vector2d& scroll,
-      float scale_delta,
-      float top_controls_delta) override {
-    EXPECT_EQ(info_.page_scale_delta, scale_delta);
-    EXPECT_EQ(info_.top_controls_delta, top_controls_delta);
-    deltas_sent_to_client_ = true;
-  }
-
   void AfterTest() override {
     EXPECT_TRUE(deltas_sent_to_client_);
   }
diff --git a/cc/trees/layer_tree_host_unittest_no_message_loop.cc b/cc/trees/layer_tree_host_unittest_no_message_loop.cc
index d5000c3..8b7b12d 100644
--- a/cc/trees/layer_tree_host_unittest_no_message_loop.cc
+++ b/cc/trees/layer_tree_host_unittest_no_message_loop.cc
@@ -63,9 +63,6 @@ class LayerTreeHostNoMessageLoopTest
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override {}
   void RequestNewOutputSurface() override {
     layer_tree_host_->SetOutputSurface(
         make_scoped_ptr<OutputSurface>(new NoMessageLoopOutputSurface));
diff --git a/cc/trees/layer_tree_host_unittest_scroll.cc b/cc/trees/layer_tree_host_unittest_scroll.cc
index dcd7153..2ac0008 100644
--- a/cc/trees/layer_tree_host_unittest_scroll.cc
+++ b/cc/trees/layer_tree_host_unittest_scroll.cc
@@ -92,7 +92,9 @@ class LayerTreeHostScrollTestScrollSimple : public LayerTreeHostScrollTest {
     }
   }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
+                           const gfx::Vector2dF& outer_delta,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float top_controls_delta) override {
     num_scrolls_++;
@@ -184,7 +186,9 @@ class LayerTreeHostScrollTestScrollMultipleRedraw
     }
   }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
+                           const gfx::Vector2dF& outer_delta,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float top_controls_delta) override {
     num_scrolls_++;
@@ -364,7 +368,9 @@ class LayerTreeHostScrollTestScrollAbortedCommit
     }
   }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
+                           const gfx::Vector2dF& outer_delta,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float top_controls_delta) override {
     num_impl_scrolls_++;
@@ -536,7 +542,9 @@ class LayerTreeHostScrollTestCaseWithChild : public LayerTreeHostScrollTest {
     final_scroll_offset_ = expected_scroll_layer_->scroll_offset();
   }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
+                           const gfx::Vector2dF& outer_delta,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float top_controls_delta) override {
     num_scrolls_++;
@@ -870,7 +878,9 @@ class ImplSidePaintingScrollTestSimple : public ImplSidePaintingScrollTest {
     }
   }
 
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
+  void ApplyViewportDeltas(const gfx::Vector2dF& inner_delta,
+                           const gfx::Vector2dF& outer_delta,
+                           const gfx::Vector2dF& elastic_overscroll_delta,
                            float scale,
                            float top_controls_delta) override {
     num_scrolls_++;
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index 89639f1..35da140 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -56,7 +56,6 @@ LayerTreeSettings::LayerTreeSettings()
       max_untiled_layer_size(gfx::Size(512, 512)),
       default_tile_grid_size(gfx::Size(256, 256)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
-      use_pinch_virtual_viewport(false),
       tiling_interest_area_viewport_multiplier(9.0f),
       skewport_target_time_in_seconds(1.0f),
       skewport_extrapolation_limit_in_content_pixels(2000),
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 1020737..d62657a 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -71,7 +71,6 @@ class CC_EXPORT LayerTreeSettings {
   gfx::Size max_untiled_layer_size;
   gfx::Size default_tile_grid_size;
   gfx::Size minimum_occlusion_tracking_size;
-  bool use_pinch_virtual_viewport;
   float tiling_interest_area_viewport_multiplier;
   float skewport_target_time_in_seconds;
   int skewport_extrapolation_limit_in_content_pixels;
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index d245ee5..d6a78e7 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1017,15 +1017,6 @@ const Experiment kExperiments[] = {
   },
 #endif  // defined(USE_ASH)
   {
-    "enable-pinch-virtual-viewport",
-    IDS_FLAGS_ENABLE_PINCH_VIRTUAL_VIEWPORT_NAME,
-    IDS_FLAGS_ENABLE_PINCH_VIRTUAL_VIEWPORT_DESCRIPTION,
-    kOsLinux | kOsWin | kOsCrOS | kOsAndroid,
-    ENABLE_DISABLE_VALUE_TYPE(
-        cc::switches::kEnablePinchVirtualViewport,
-        cc::switches::kDisablePinchVirtualViewport),
-  },
-  {
     "enable-viewport-meta",
     IDS_FLAGS_ENABLE_VIEWPORT_META_NAME,
     IDS_FLAGS_ENABLE_VIEWPORT_META_DESCRIPTION,
diff --git a/chrome/browser/chromeos/login/chrome_restart_request.cc b/chrome/browser/chromeos/login/chrome_restart_request.cc
index 8c7f626..b31f3fa 100644
--- a/chrome/browser/chromeos/login/chrome_restart_request.cc
+++ b/chrome/browser/chromeos/login/chrome_restart_request.cc
@@ -186,11 +186,9 @@ std::string DeriveCommandLine(const GURL& start_url,
     cc::switches::kCompositeToMailbox,
     cc::switches::kDisableCompositedAntialiasing,
     cc::switches::kDisableMainFrameBeforeActivation,
-    cc::switches::kDisablePinchVirtualViewport,
     cc::switches::kDisableThreadedAnimation,
     cc::switches::kEnableBeginFrameScheduling,
     cc::switches::kEnableGpuBenchmarking,
-    cc::switches::kEnablePinchVirtualViewport,
     cc::switches::kEnablePropertyTreeVerification,
     cc::switches::kEnableMainFrameBeforeActivation,
     cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
diff --git a/chrome/renderer/autofill/page_click_tracker_browsertest.cc b/chrome/renderer/autofill/page_click_tracker_browsertest.cc
index 9ae73b1..d868870 100644
--- a/chrome/renderer/autofill/page_click_tracker_browsertest.cc
+++ b/chrome/renderer/autofill/page_click_tracker_browsertest.cc
@@ -55,7 +55,6 @@ class PageClickTrackerTest : public ChromeRenderViewTest {
 
     // Must be set before loading HTML.
     view_->GetWebView()->setDefaultPageScaleLimits(1, 4);
-    view_->GetWebView()->settings()->setPinchVirtualViewportEnabled(true);
 
     LoadHTML("<form>"
              "  <input type='text' id='text_1'></input><br>"
diff --git a/components/html_viewer/web_layer_tree_view_impl.cc b/components/html_viewer/web_layer_tree_view_impl.cc
index 51f424b..98885cd 100644
--- a/components/html_viewer/web_layer_tree_view_impl.cc
+++ b/components/html_viewer/web_layer_tree_view_impl.cc
@@ -101,13 +101,6 @@ void WebLayerTreeViewImpl::ApplyViewportDeltas(
       top_controls_delta);
 }
 
-void WebLayerTreeViewImpl::ApplyViewportDeltas(
-    const gfx::Vector2d& scroll_delta,
-    float page_scale,
-    float top_controls_delta) {
-  widget_->applyViewportDeltas(scroll_delta, page_scale, top_controls_delta);
-}
-
 void WebLayerTreeViewImpl::RequestNewOutputSurface() {
   if (output_surface_.get())
     layer_tree_host_->SetOutputSurface(output_surface_.Pass());
diff --git a/components/html_viewer/web_layer_tree_view_impl.h b/components/html_viewer/web_layer_tree_view_impl.h
index 709d331..1a09bd4 100644
--- a/components/html_viewer/web_layer_tree_view_impl.h
+++ b/components/html_viewer/web_layer_tree_view_impl.h
@@ -58,9 +58,6 @@ class WebLayerTreeViewImpl : public blink::WebLayerTreeView,
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override;
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override;
   void RequestNewOutputSurface() override;
   void DidFailToInitializeOutputSurface() override;
   void DidInitializeOutputSurface() override;
diff --git a/content/browser/gpu/compositor_util.cc b/content/browser/gpu/compositor_util.cc
index a652c39..2e46bda 100644
--- a/content/browser/gpu/compositor_util.cc
+++ b/content/browser/gpu/compositor_util.cc
@@ -167,19 +167,6 @@ const GpuFeatureInfo GetGpuFeatureInfo(size_t index, bool* eof) {
 
 }  // namespace
 
-bool IsPinchVirtualViewportEnabled() {
-  const base::CommandLine& command_line =
-      *base::CommandLine::ForCurrentProcess();
-
-  // Command line switches take precedence over platform default.
-  if (command_line.HasSwitch(cc::switches::kDisablePinchVirtualViewport))
-    return false;
-  if (command_line.HasSwitch(cc::switches::kEnablePinchVirtualViewport))
-    return true;
-
-  return true;
-}
-
 bool IsPropertyTreeVerificationEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
diff --git a/content/browser/gpu/compositor_util.h b/content/browser/gpu/compositor_util.h
index 3400fba..1475e6b 100644
--- a/content/browser/gpu/compositor_util.h
+++ b/content/browser/gpu/compositor_util.h
@@ -13,10 +13,6 @@ namespace content {
 // Note: When adding a function here, please make sure the logic is not
 // duplicated in the renderer.
 
-// Returns true if the virtual viewport model of pinch-to-zoom is on (via
-// flags, or platform default).
-CONTENT_EXPORT bool IsPinchVirtualViewportEnabled();
-
 // Returns true if property tree verification is enabled (via flags or platform
 // default).
 CONTENT_EXPORT bool IsPropertyTreeVerificationEnabled();
diff --git a/content/browser/renderer_host/compositor_impl_android.h b/content/browser/renderer_host/compositor_impl_android.h
index 672a566..4bba37c 100644
--- a/content/browser/renderer_host/compositor_impl_android.h
+++ b/content/browser/renderer_host/compositor_impl_android.h
@@ -77,9 +77,6 @@ class CONTENT_EXPORT CompositorImpl
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override {}
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override;
   void DidFailToInitializeOutputSurface() override;
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index dc81915..1417f0f 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1100,9 +1100,6 @@ StoragePartition* RenderProcessHostImpl::GetStoragePartition() const {
 }
 
 static void AppendCompositorCommandLineFlags(base::CommandLine* command_line) {
-  if (IsPinchVirtualViewportEnabled())
-    command_line->AppendSwitch(cc::switches::kEnablePinchVirtualViewport);
-
   if (IsPropertyTreeVerificationEnabled())
     command_line->AppendSwitch(cc::switches::kEnablePropertyTreeVerification);
 
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index 5443761..d5ef454 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -435,10 +435,7 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
       || (content::IsImplSidePaintingEnabled() &&
           !command_line.HasSwitch(switches::kDisableTextBlobs));
 
-  if (IsPinchVirtualViewportEnabled()) {
-    prefs.pinch_virtual_viewport_enabled = true;
-    prefs.pinch_overlay_scrollbar_thickness = 10;
-  }
+  prefs.pinch_overlay_scrollbar_thickness = 10;
   prefs.use_solid_color_scrollbars = ui::IsOverlayScrollbarEnabled();
 
 #if defined(OS_ANDROID)
diff --git a/content/public/common/common_param_traits_macros.h b/content/public/common/common_param_traits_macros.h
index 7c87f64..9c8e453 100644
--- a/content/public/common/common_param_traits_macros.h
+++ b/content/public/common/common_param_traits_macros.h
@@ -143,7 +143,6 @@ IPC_STRUCT_TRAITS_BEGIN(content::WebPreferences)
   IPC_STRUCT_TRAITS_MEMBER(webaudio_enabled)
   IPC_STRUCT_TRAITS_MEMBER(experimental_webgl_enabled)
   IPC_STRUCT_TRAITS_MEMBER(pepper_3d_enabled)
-  IPC_STRUCT_TRAITS_MEMBER(pinch_virtual_viewport_enabled)
   IPC_STRUCT_TRAITS_MEMBER(pinch_overlay_scrollbar_thickness)
   IPC_STRUCT_TRAITS_MEMBER(use_solid_color_scrollbars)
   IPC_STRUCT_TRAITS_MEMBER(flash_3d_enabled)
diff --git a/content/public/common/web_preferences.cc b/content/public/common/web_preferences.cc
index d557de2..6279aba 100644
--- a/content/public/common/web_preferences.cc
+++ b/content/public/common/web_preferences.cc
@@ -184,7 +184,6 @@ WebPreferences::WebPreferences()
       smart_insert_delete_enabled(false),
 #endif
       spatial_navigation_enabled(false),
-      pinch_virtual_viewport_enabled(false),
       pinch_overlay_scrollbar_thickness(0),
       use_solid_color_scrollbars(false),
       navigate_on_drag_drop(true),
diff --git a/content/public/common/web_preferences.h b/content/public/common/web_preferences.h
index 254d970..5dfc5d5 100644
--- a/content/public/common/web_preferences.h
+++ b/content/public/common/web_preferences.h
@@ -176,7 +176,6 @@ struct CONTENT_EXPORT WebPreferences {
   bool initialize_at_minimum_page_scale;
   bool smart_insert_delete_enabled;
   bool spatial_navigation_enabled;
-  bool pinch_virtual_viewport_enabled;
   int pinch_overlay_scrollbar_thickness;
   bool use_solid_color_scrollbars;
   bool navigate_on_drag_drop;
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 7c868b6..7018c79 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -310,8 +310,6 @@ void RenderWidgetCompositor::Initialize() {
         settings.top_controls_hide_threshold = hide_threshold;
   }
 
-  settings.use_pinch_virtual_viewport =
-      cmd->HasSwitch(cc::switches::kEnablePinchVirtualViewport);
   settings.verify_property_trees =
       cmd->HasSwitch(cc::switches::kEnablePropertyTreeVerification) &&
       settings.impl_side_painting;
@@ -431,7 +429,7 @@ void RenderWidgetCompositor::Initialize() {
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::THINNING;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
-  } else if (settings.use_pinch_virtual_viewport) {
+  } else {
     settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }
@@ -674,6 +672,9 @@ void RenderWidgetCompositor::registerViewportLayers(
     const blink::WebLayer* innerViewportScrollLayer,
     const blink::WebLayer* outerViewportScrollLayer) {
   layer_tree_host_->RegisterViewportLayers(
+      // TODO(bokan): This check can probably be removed now, but it looks
+      // like overscroll elasticity may still be NULL until PinchViewport
+      // registers its layers.
       // The scroll elasticity layer will only exist when using pinch virtual
       // viewports.
       overscrollElasticityLayer
@@ -683,6 +684,9 @@ void RenderWidgetCompositor::registerViewportLayers(
       static_cast<const cc_blink::WebLayerImpl*>(pageScaleLayer)->layer(),
       static_cast<const cc_blink::WebLayerImpl*>(innerViewportScrollLayer)
           ->layer(),
+      // TODO(bokan): This check can probably be removed now, but it looks
+      // like overscroll elasticity may still be NULL until PinchViewport
+      // registers its layers.
       // The outer viewport layer will only exist when using pinch virtual
       // viewports.
       outerViewportScrollLayer
@@ -868,16 +872,6 @@ void RenderWidgetCompositor::ApplyViewportDeltas(
       top_controls_delta);
 }
 
-void RenderWidgetCompositor::ApplyViewportDeltas(
-    const gfx::Vector2d& scroll_delta,
-    float page_scale,
-    float top_controls_delta) {
-  widget_->webwidget()->applyViewportDeltas(
-      scroll_delta,
-      page_scale,
-      top_controls_delta);
-}
-
 void RenderWidgetCompositor::RequestNewOutputSurface() {
   // If the host is closing, then no more compositing is possible.  This
   // prevents shutdown races between handling the close message and
diff --git a/content/renderer/gpu/render_widget_compositor.h b/content/renderer/gpu/render_widget_compositor.h
index a6d1981..0ab2dbb 100644
--- a/content/renderer/gpu/render_widget_compositor.h
+++ b/content/renderer/gpu/render_widget_compositor.h
@@ -145,9 +145,6 @@ class CONTENT_EXPORT RenderWidgetCompositor
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override;
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override;
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override;
   void DidFailToInitializeOutputSurface() override;
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 0e6b85e..5c49183 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1113,8 +1113,6 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
   WebNetworkStateNotifier::setOnLine(prefs.is_online);
   WebNetworkStateNotifier::setWebConnectionType(
       NetConnectionTypeToWebConnectionType(prefs.connection_type));
-  settings->setPinchVirtualViewportEnabled(
-      prefs.pinch_virtual_viewport_enabled);
 
   settings->setPinchOverlayScrollbarThickness(
       prefs.pinch_overlay_scrollbar_thickness);
diff --git a/content/test/web_layer_tree_view_impl_for_testing.cc b/content/test/web_layer_tree_view_impl_for_testing.cc
index 2538804..ecce63c 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.cc
+++ b/content/test/web_layer_tree_view_impl_for_testing.cc
@@ -145,11 +145,6 @@ void WebLayerTreeViewImplForTesting::ApplyViewportDeltas(
     float top_controls_delta) {
 }
 
-void WebLayerTreeViewImplForTesting::ApplyViewportDeltas(
-    const gfx::Vector2d& scroll_delta,
-    float page_scale,
-    float top_controls_delta) {}
-
 void WebLayerTreeViewImplForTesting::RequestNewOutputSurface() {
   bool flipped_output_surface = false;
   layer_tree_host_->SetOutputSurface(
diff --git a/content/test/web_layer_tree_view_impl_for_testing.h b/content/test/web_layer_tree_view_impl_for_testing.h
index 9c98089..539c320 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.h
+++ b/content/test/web_layer_tree_view_impl_for_testing.h
@@ -74,9 +74,6 @@ class WebLayerTreeViewImplForTesting
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override;
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override;
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override {}
   void DidFailToInitializeOutputSurface() override;
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index 7b0809b..3101bc2 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -289,9 +289,6 @@ class COMPOSITOR_EXPORT Compositor
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
-  void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
-                           float page_scale,
-                           float top_controls_delta) override {}
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override;
   void DidFailToInitializeOutputSurface() override;