Revert "cc: Clamp texture coordinates in all tile shaders"

cc/gl_renderer.cc

 // Copyright 2010 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/gl_renderer.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 874 matching lines @@
         // Map device space quad to local space. deviceTransform has no 3d component since it was flattened, so we don't need to project.
         // We should have already checked that the transform was uninvertible above.
         gfx::Transform inverseDeviceTransform(gfx::Transform::kSkipInitialization);
         bool didInvert = deviceTransform.GetInverse(&inverseDeviceTransform);
         DCHECK(didInvert);
         localQuad = MathUtil::mapQuad(inverseDeviceTransform, deviceQuad.ToQuadF(), clipped);
 
         // We should not DCHECK(!clipped) here, because anti-aliasing inflation may cause deviceQuad to become
         // clipped. To our knowledge this scenario does not need to be handled differently than the unclipped case.
     } else {
+        // Move fragment shader transform to vertex shader. We can do this while
+        // still producing correct results as fragmentTexTransformLocation
+        // should always be non-negative when tiles are transformed in a way
+        // that could result in sampling outside the layer.
+        vertexTexScaleX *= fragmentTexScaleX;
+        vertexTexScaleY *= fragmentTexScaleY;
+        vertexTexTranslateX *= fragmentTexScaleX;
+        vertexTexTranslateY *= fragmentTexScaleY;
+        vertexTexTranslateX += fragmentTexTranslateX;
+        vertexTexTranslateY += fragmentTexTranslateY;
+
         GLC(context(), context()->uniform4f(uniforms.vertexTexTransformLocation, vertexTexTranslateX, vertexTexTranslateY, vertexTexScaleX, vertexTexScaleY));
-        GLC(context(), context()->uniform4f(uniforms.fragmentTexTransformLocation, fragmentTexTranslateX, fragmentTexTranslateY, fragmentTexScaleX, fragmentTexScaleY));
 
         localQuad = gfx::RectF(tileRect);
     }
 
     // Normalize to tileRect.
     localQuad.Scale(1.0f / tileRect.width(), 1.0f / tileRect.height());
 
     setShaderOpacity(quad->opacity(), uniforms.alphaLocation);
     setShaderQuadF(localQuad, uniforms.pointLocation);
 
@@ skipping 906 matching lines @@
 
     releaseRenderPassTextures();
 }
 
 bool GLRenderer::isContextLost()
 {
     return (m_context->getGraphicsResetStatusARB() != GL_NO_ERROR);
 }
 
 }  // namespace cc