[Android] Isolate OverscrollRefresh from device density

Make the OverscrollRefresh effect take the target drag threshold as a
parameter. This isolates it from direct dependencies on the device scale
factor, making associated unit tests determnistics across all devices.

BUG=435125

Review URL: https://codereview.chromium.org/748433002

Cr-Commit-Position: refs/heads/master@{#305026}

content/browser/android/overscroll_controller_android.cc

@@ -21,6 +21,10 @@ namespace {
 // Used for conditional creation of EdgeEffect types for the overscroll glow.
 const int kAndroidLSDKVersion = 21;
 
+// Default offset in dips from the top of the view beyond which the refresh
+// action will be activated.
+const int kDefaultRefreshDragTargetDips = 64;
+
 scoped_ptr<EdgeEffectBase> CreateGlowEdgeEffect(
     ui::SystemUIResourceManager* resource_manager,
     float dpi_scale) {
@@ -47,7 +51,9 @@ OverscrollControllerAndroid::OverscrollControllerAndroid(
       glow_effect_(base::Bind(&CreateGlowEdgeEffect,
                               &compositor->GetSystemUIResourceManager(),
                               dpi_scale_)),
-      refresh_effect_(&compositor->GetSystemUIResourceManager(), this),
+      refresh_effect_(&compositor->GetSystemUIResourceManager(),
+                      this,
+                      kDefaultRefreshDragTargetDips * dpi_scale),
       triggered_refresh_active_(false) {
   DCHECK(web_contents);
 }

content/browser/android/overscroll_refresh.cc

@@ -8,7 +8,6 @@
 #include "cc/trees/layer_tree_host.h"
 #include "content/browser/android/animation_utils.h"
 #include "ui/base/android/system_ui_resource_manager.h"
-#include "ui/gfx/screen.h"
 
 using std::abs;
 using std::max;
@@ -21,10 +20,6 @@ const ui::SystemUIResourceType kIdleResourceType = ui::OVERSCROLL_REFRESH_IDLE;
 const ui::SystemUIResourceType kActiveResourceType =
     ui::OVERSCROLL_REFRESH_ACTIVE;
 
-// Default offset in dips from the top of the view to where the progress spinner
-// should stop.
-const int kDefaultSpinnerTargetDips = 64;
-
 // Drag movement multiplier between user input and effect translation.
 const float kDragRate = .5f;
 
@@ -111,14 +106,11 @@ void UpdateLayer(cc::UIResourceLayer* layer,
 
 class OverscrollRefresh::Effect {
  public:
-  Effect(ui::SystemUIResourceManager* resource_manager)
+  Effect(ui::SystemUIResourceManager* resource_manager, float target_drag)
       : resource_manager_(resource_manager),
         idle_layer_(cc::UIResourceLayer::Create()),
         active_layer_(cc::UIResourceLayer::Create()),
-        target_drag_(kDefaultSpinnerTargetDips *
-                     gfx::Screen::GetNativeScreen()
-                         ->GetPrimaryDisplay()
-                         .device_scale_factor()),
+        target_drag_(target_drag),
         drag_(0),
         idle_alpha_(0),
         active_alpha_(0),
@@ -361,11 +353,12 @@ class OverscrollRefresh::Effect {
 
 OverscrollRefresh::OverscrollRefresh(
     ui::SystemUIResourceManager* resource_manager,
-    OverscrollRefreshClient* client)
+    OverscrollRefreshClient* client,
+    float target_drag_offset_pixels)
     : client_(client),
       scrolled_to_top_(true),
       scroll_consumption_state_(DISABLED),
-      effect_(new Effect(resource_manager)) {
+      effect_(new Effect(resource_manager, target_drag_offset_pixels)) {
   DCHECK(client);
 }
 

content/browser/android/overscroll_refresh.h

@@ -44,8 +44,12 @@ class CONTENT_EXPORT OverscrollRefreshClient {
 // and beyond a particular threshold when released.
 class CONTENT_EXPORT OverscrollRefresh {
  public:
+  // Both |resource_manager| and |client| must not be null.
+  // |target_drag_offset_pixels| is the threshold beyond which the effect
+  // will trigger a refresh action when released.
   OverscrollRefresh(ui::SystemUIResourceManager* resource_manager,
-                    OverscrollRefreshClient* client);
+                    OverscrollRefreshClient* client,
+                    float target_drag_offset_pixels);
   ~OverscrollRefresh();
 
   // Scroll event stream listening methods.

content/browser/android/overscroll_refresh_unittest.cc

@@ -9,6 +9,8 @@
 
 namespace content {
 
+const float kDragTargetPixels = 100;
+
 gfx::SizeF DefaultViewportSize() {
   return gfx::SizeF(512, 512);
 }
@@ -49,7 +51,7 @@ class OverscrollRefreshTest : public OverscrollRefreshClient,
 };
 
 TEST_F(OverscrollRefreshTest, Basic) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
 
   gfx::Vector2dF origin_scroll_offset;
   effect.UpdateDisplay(DefaultViewportSize(), origin_scroll_offset);
@@ -112,7 +114,7 @@ TEST_F(OverscrollRefreshTest, Basic) {
 }
 
 TEST_F(OverscrollRefreshTest, AnimationTerminatesEvenIfRefreshNeverTerminates) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
   ASSERT_FALSE(effect.WillHandleScrollUpdate(gfx::Vector2dF(0, 10)));
@@ -144,7 +146,7 @@ TEST_F(OverscrollRefreshTest, AnimationTerminatesEvenIfRefreshNeverTerminates) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfBelowThreshold) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
   ASSERT_FALSE(effect.WillHandleScrollUpdate(gfx::Vector2dF(0, 10)));
@@ -159,7 +161,7 @@ TEST_F(OverscrollRefreshTest, NotTriggeredIfBelowThreshold) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialYOffsetIsNotZero) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
 
   // A positive y scroll offset at the start of scroll will prevent activation,
   // even if the subsequent scroll overscrolls upward.
@@ -180,7 +182,7 @@ TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialYOffsetIsNotZero) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollDownward) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
 
@@ -199,7 +201,7 @@ TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollDownward) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollOrTouchConsumed) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
   ASSERT_FALSE(effect.WillHandleScrollUpdate(gfx::Vector2dF(0, 10)));
@@ -220,7 +222,7 @@ TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollOrTouchConsumed) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollsJanked) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
   ASSERT_FALSE(effect.WillHandleScrollUpdate(gfx::Vector2dF(0, 10)));
@@ -237,7 +239,7 @@ TEST_F(OverscrollRefreshTest, NotTriggeredIfInitialScrollsJanked) {
 }
 
 TEST_F(OverscrollRefreshTest, NotTriggeredIfFlungDownward) {
-  OverscrollRefresh effect(this, this);
+  OverscrollRefresh effect(this, this, kDragTargetPixels);
   effect.UpdateDisplay(DefaultViewportSize(), gfx::Vector2dF());
   effect.OnScrollBegin();
   ASSERT_FALSE(effect.WillHandleScrollUpdate(gfx::Vector2dF(0, 10)));