cc: Return whether any layer was scrolled from InputHandlerClient::scrollBy.

cc/layer_tree_host_impl_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layer_tree_host_impl.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 461 matching lines @@
 
     // This point would fall into the non-fast scrollable region except that we've moved the layer down by 25 pixels.
     EXPECT_EQ(m_hostImpl->scrollBegin(gfx::Point(40, 10), InputHandlerClient::Wheel), InputHandlerClient::ScrollStarted);
     m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(0, 1));
     m_hostImpl->scrollEnd();
 
     // This point is still inside the non-fast region.
     EXPECT_EQ(m_hostImpl->scrollBegin(gfx::Point(10, 10), InputHandlerClient::Wheel), InputHandlerClient::ScrollOnMainThread);
 }
 
+TEST_P(LayerTreeHostImplTest, scrollByReturnsCorrectValue)
+{
+    setupScrollAndContentsLayers(gfx::Size(200, 200));
+    m_hostImpl->setViewportSize(gfx::Size(100, 100), gfx::Size(100, 100));
+
+    initializeRendererAndDrawFrame();
+
+    EXPECT_EQ(InputHandlerClient::ScrollStarted,
+        m_hostImpl->scrollBegin(gfx::Point(0, 0), InputHandlerClient::Gesture));
+
+    // Trying to scroll to the left/top will not succeed.
+    EXPECT_FALSE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(-10, 0)));
+    EXPECT_FALSE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(0, -10)));
+    EXPECT_FALSE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(-10, -10)));
+
+    // Scrolling to the right/bottom will succeed.
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(10, 0)));
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(0, 10)));
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(10, 10)));
+
+    // Scrolling to left/top will now succeed.
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(-10, 0)));
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(0, -10)));
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(-10, -10)));
+
+    // Trying to scroll more than the available space will also succeed.
+    EXPECT_TRUE(m_hostImpl->scrollBy(gfx::Point(), gfx::Vector2d(5000, 5000)));
+}
+
 TEST_P(LayerTreeHostImplTest, maxScrollOffsetChangedByDeviceScaleFactor)
 {
     setupScrollAndContentsLayers(gfx::Size(100, 100));
 
     float deviceScaleFactor = 2;
     gfx::Size layoutViewport(25, 25);
     gfx::Size deviceViewport(gfx::ToFlooredSize(gfx::ScaleSize(layoutViewport, deviceScaleFactor)));
     m_hostImpl->setViewportSize(layoutViewport, deviceViewport);
     m_hostImpl->setDeviceScaleFactor(deviceScaleFactor);
     EXPECT_EQ(m_hostImpl->rootLayer()->maxScrollOffset(), gfx::Vector2d(25, 25));
@@ skipping 3947 matching lines @@
         testCaseIndex++;
     }
 }
 
 INSTANTIATE_TEST_CASE_P(LayerTreeHostImplTests,
                         LayerTreeHostImplTest,
                         ::testing::Values(false, true));
 
 }  // namespace
 }  // namespace cc