WebVR: Add explicit precision to all shaders to avoid Mali GPU crash

chrome/browser/android/vr_shell/vr_shell_renderer.cc

 // Copyright 2016 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 "chrome/browser/android/vr_shell/vr_shell_renderer.h"
 
 #include <math.h>
 #include <algorithm>
 #include <string>
 
@@ skipping 59 matching lines @@
 #define VOID_OFFSET(x) reinterpret_cast<void*>(x)
 
 const char* GetShaderSource(vr_shell::ShaderID shader) {
   switch (shader) {
     case vr_shell::ShaderID::TEXTURE_QUAD_VERTEX_SHADER:
     case vr_shell::ShaderID::RETICLE_VERTEX_SHADER:
     case vr_shell::ShaderID::LASER_VERTEX_SHADER:
     case vr_shell::ShaderID::CONTROLLER_VERTEX_SHADER:
       return SHADER(
           /* clang-format off */
+          precision mediump float;
           uniform mat4 u_ModelViewProjMatrix;
           attribute vec4 a_Position;
           attribute vec2 a_TexCoordinate;
           varying vec2 v_TexCoordinate;
 
           void main() {
             v_TexCoordinate = a_TexCoordinate;
             gl_Position = u_ModelViewProjMatrix * a_Position;
           }
           /* clang-format on */);
     case vr_shell::ShaderID::GRADIENT_QUAD_VERTEX_SHADER:
     case vr_shell::ShaderID::GRADIENT_GRID_VERTEX_SHADER:
       return SHADER(
           /* clang-format off */
+          precision mediump float;
           uniform mat4 u_ModelViewProjMatrix;
           uniform float u_SceneRadius;
           attribute vec4 a_Position;
           varying vec2 v_GridPosition;
 
           void main() {
             v_GridPosition = a_Position.xy / u_SceneRadius;
             gl_Position = u_ModelViewProjMatrix * a_Position;
           }
           /* clang-format on */);
@@ skipping 11 matching lines @@
             vec2 scaledTex =
                 vec2(u_CopyRect[0] + v_TexCoordinate.x * u_CopyRect[2],
                      u_CopyRect[1] + v_TexCoordinate.y * u_CopyRect[3]);
             lowp vec4 color = texture2D(u_Texture, scaledTex);
             gl_FragColor = vec4(color.xyz, color.w * opacity);
           }
           /* clang-format on */);
     case vr_shell::ShaderID::WEBVR_VERTEX_SHADER:
       return SHADER(
           /* clang-format off */
+          precision mediump float;
           attribute vec3 a_Position;
           attribute vec2 a_TexCoordinate;
-          varying vec2 v_TexCoordinate;
+          varying highp vec2 v_TexCoordinate;
 
           void main() {
             v_TexCoordinate = a_TexCoordinate;
             gl_Position = vec4(a_Position * 2.0, 1.0);
           }
           /* clang-format on */);
     case vr_shell::ShaderID::WEBVR_FRAGMENT_SHADER:
       return OEIE_SHADER(
           /* clang-format off */
           precision highp float;
           uniform samplerExternalOES u_Texture;
           varying vec2 v_TexCoordinate;
 
           void main() {
             gl_FragColor = texture2D(u_Texture, v_TexCoordinate);
           }
           /* clang-format on */);
     case vr_shell::ShaderID::RETICLE_FRAGMENT_SHADER:
       return SHADER(
           /* clang-format off */
+          precision mediump float;
           varying mediump vec2 v_TexCoordinate;
           uniform lowp vec4 color;
           uniform mediump float ring_diameter;
           uniform mediump float inner_hole;
           uniform mediump float inner_ring_end;
           uniform mediump float inner_ring_thickness;
           uniform mediump float mid_ring_end;
           uniform mediump float mid_ring_opacity;
 
           void main() {
@@ skipping 53 matching lines @@
           void main() {
             float edgeColorWeight = clamp(length(v_GridPosition), 0.0, 1.0);
             float centerColorWeight = 1.0 - edgeColorWeight;
             gl_FragColor = (u_CenterColor * centerColorWeight +
                 u_EdgeColor * edgeColorWeight) * vec4(1.0, 1.0, 1.0, u_Opacity);
           }
           /* clang-format on */);
     case vr_shell::ShaderID::CONTROLLER_FRAGMENT_SHADER:
       return SHADER(
           /* clang-format off */
+          precision mediump float;
           uniform sampler2D u_texture;
           varying vec2 v_TexCoordinate;
 
           void main() {
             gl_FragColor = texture2D(u_texture, v_TexCoordinate);
           }
           /* clang-format on */);
     default:
       LOG(ERROR) << "Shader source requested for unknown shader";
       return "";
@@ skipping 504 matching lines @@
       laser_renderer_(base::MakeUnique<LaserRenderer>()),
       controller_renderer_(base::MakeUnique<ControllerRenderer>()),
       gradient_quad_renderer_(base::MakeUnique<GradientQuadRenderer>()),
       gradient_grid_renderer_(base::MakeUnique<GradientGridRenderer>()) {
   BaseQuadRenderer::SetVertexBuffer();
 }
 
 VrShellRenderer::~VrShellRenderer() = default;
 
 }  // namespace vr_shell