Get correct GLVersion for Mesa to avoid GrContext creation failure

src/gpu/gl/GrGLUtil.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLUtil.h"
 
@@ skipping 30 matching lines @@
         if (NULL != location) {
             GrPrintf(" at\n\t%s", location);
         }
         if (NULL != call) {
             GrPrintf("\n\t\t%s", call);
         }
         GrPrintf("\n");
     }
 }
 
+namespace {
+bool get_gl_version_for_mesa(const int mesaMajorVersion,
+                             int* major,
+                             int* minor) {
+    switch (mesaMajorVersion) {
+        case 2:
+        case 3:
+        case 4:
+        case 5:
+        case 6:
+            *major = 1;
+            *minor = mesaMajorVersion - 1;
+            return true;
+        case 7:
+            *major = 2;
+            *minor = 1;
+            return true;
+        case 8:
+            *major = 3;
+            *minor = 0;
+            return true;
+        case 9:
+            *major = 3;
+            *minor = 1;
+            return true;
+        default:
+            return false;
+    }
+}
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #if GR_GL_LOG_CALLS
     bool gLogCallsGL = !!(GR_GL_LOG_CALLS_START);
 #endif
 
 #if GR_GL_CHECK_ERROR
     bool gCheckErrorGL = !!(GR_GL_CHECK_ERROR_START);
 #endif
 
@@ skipping 31 matching lines @@
 }
 
 GrGLVersion GrGLGetVersionFromString(const char* versionString) {
     if (NULL == versionString) {
         GrAssert(!"NULL GL version string.");
         return 0;
     }
 
     int major, minor;
 
-    int n = sscanf(versionString, "%d.%d", &major, &minor);
+    // check for mesa
+    int mesaMajor, mesaMinor;
+    int n = sscanf(versionString, "%d.%d Mesa %d.%d", &major, &minor,
+                                                     &mesaMajor, &mesaMinor);
+    if (4 == n) {
+        if (get_gl_version_for_mesa(mesaMajor, &major, &minor)) {
+            return GR_GL_VER(major, minor);
+        } else {
+            return 0;
+        }
+    }
+
+    n = sscanf(versionString, "%d.%d", &major, &minor);
     if (2 == n) {
         return GR_GL_VER(major, minor);
     }
 
     char profile[2];
     n = sscanf(versionString, "OpenGL ES-%c%c %d.%d", profile, profile+1,
                &major, &minor);
     if (4 == n) {
         return GR_GL_VER(major, minor);
     }
@@ skipping 66 matching lines @@
     const GrGLubyte* v;
     GR_GL_CALL_RET(gl, v, GetString(GR_GL_SHADING_LANGUAGE_VERSION));
     return GrGLGetGLSLVersionFromString((const char*) v);
 }
 
 GrGLVendor GrGLGetVendor(const GrGLInterface* gl) {
     const GrGLubyte* v;
     GR_GL_CALL_RET(gl, v, GetString(GR_GL_VENDOR));
     return GrGLGetVendorFromString((const char*) v);
 }