Allow using a larger-than-necessary texture as cached render pass backing

cc/shader.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/shader.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include <public/WebGraphicsContext3D.h>
 
@@ skipping 153 matching lines @@
         uniform vec4 texTransform[8];
         varying vec2 v_texCoord;
         void main()
         {
             gl_Position = matrix[int(a_index)] * a_position;
             v_texCoord = a_texCoord * texTransform[int(a_index)].zw + texTransform[int(a_index)].xy;
         }
     );
 }
 
-VertexShaderQuad::VertexShaderQuad()
-    : m_matrixLocation(-1)
-    , m_pointLocation(-1)
-{
-}
-
 std::string VertexShaderPosTexIdentity::getShaderString() const
 {
     return SHADER(
         attribute vec4 a_position;
         varying vec2 v_texCoord;
         void main()
         {
             gl_Position = a_position;
             v_texCoord = (a_position.xy + vec2(1.0)) * 0.5;
         }
     );
 }
 
+VertexShaderQuad::VertexShaderQuad()
+    : m_matrixLocation(-1)
+    , m_pointLocation(-1)
+    , m_texScaleLocation(-1)
+{
+}
+
 void VertexShaderQuad::init(WebGraphicsContext3D* context, unsigned program, bool usingBindUniform, int* baseUniformIndex)
 {
     static const char* shaderUniforms[] = {
         "matrix",
         "point",
+        "texScale",
     };
-    int locations[2];
+    int locations[3];
 
     getProgramUniformLocations(context, program, shaderUniforms, arraysize(shaderUniforms), arraysize(locations), locations, usingBindUniform, baseUniformIndex);
 
     m_matrixLocation = locations[0];
     m_pointLocation = locations[1];
-    DCHECK(m_matrixLocation != -1 && m_pointLocation != -1);
+    m_texScaleLocation = locations[2];
+    DCHECK_NE(m_matrixLocation, -1);
+    DCHECK_NE(m_pointLocation, -1);
+    DCHECK_NE(m_texScaleLocation, -1);
 }
 
 std::string VertexShaderQuad::getShaderString() const
 {
     return SHADER(
         attribute vec4 a_position;
         attribute vec2 a_texCoord;
         uniform mat4 matrix;
         uniform vec2 point[4];
+        uniform vec2 texScale;
         varying vec2 v_texCoord;
         void main()
         {
             vec2 complement = abs(a_texCoord - 1.0);
             vec4 pos = vec4(0.0, 0.0, a_position.z, a_position.w);
             pos.xy += (complement.x * complement.y) * point[0];
             pos.xy += (a_texCoord.x * complement.y) * point[1];
             pos.xy += (a_texCoord.x * a_texCoord.y) * point[2];
             pos.xy += (complement.x * a_texCoord.y) * point[3];
             gl_Position = matrix * pos;
-            v_texCoord = pos.xy + vec2(0.5);
+            v_texCoord = (pos.xy + vec2(0.5)) * texScale;
         }
     );
 }
 
 VertexShaderTile::VertexShaderTile()
     : m_matrixLocation(-1)
     , m_pointLocation(-1)
     , m_vertexTexTransformLocation(-1)
 {
 }
@@ skipping 632 matching lines @@
             vec4 color2 = color;
             vec2 texCoord = clamp(v_texCoord, 0.0, 1.0) * texTransform.zw + texTransform.xy;
             vec2 coord = mod(floor(texCoord * frequency * 2.0), 2.0);
             float picker = abs(coord.x - coord.y);
             gl_FragColor = mix(color1, color2, picker) * alpha;
         }
     );
 }
 
 }  // namespace cc