Added disabling EGL extensions support with --disable-extensions.

ui/gl/gl_egl_api_implementation.cc

Index: ui/gl/gl_egl_api_implementation.cc
diff --git a/ui/gl/gl_egl_api_implementation.cc b/ui/gl/gl_egl_api_implementation.cc
index 53a1bf63816d6dc399f7dd4ede5de7a2161dd42c..8acaf0f460d034f71ace4701402c69fc6e69a3d6 100644
--- a/ui/gl/gl_egl_api_implementation.cc
+++ b/ui/gl/gl_egl_api_implementation.cc
@@ -3,6 +3,11 @@
 // found in the LICENSE file.
 
 #include "ui/gl/gl_egl_api_implementation.h"
+
+#include "base/command_line.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "ui/gl/gl_context.h"
 #include "ui/gl/gl_implementation.h"
 
 namespace gfx {
@@ -16,6 +21,8 @@ void InitializeStaticGLBindingsEGL() {
   g_real_egl->Initialize(&g_driver_egl);
   g_current_egl_context = g_real_egl;
   g_driver_egl.InitializeStaticBindings();
+
+  g_real_egl->InitializeFilteredExtensions();
 }
 
 void InitializeDebugGLBindingsEGL() {
@@ -55,7 +62,56 @@ RealEGLApi::~RealEGLApi() {
 }
 
 void RealEGLApi::Initialize(DriverEGL* driver) {
+  InitializeWithCommandLine(driver, base::CommandLine::ForCurrentProcess());
+}
+
+void RealEGLApi::InitializeWithCommandLine(DriverEGL* driver,
+                                           base::CommandLine* command_line) {
+  DCHECK(command_line);
   InitializeBase(driver);
+
+  const std::string disabled_extensions = command_line->GetSwitchValueASCII(
+      switches::kDisableGLExtensions);
+  if (!disabled_extensions.empty()) {
+    Tokenize(disabled_extensions, ", ;", &disabled_exts_);
+  }
+}
+
+void RealEGLApi::InitializeFilteredExtensions() {
+  if (!disabled_exts_.empty() && filtered_exts_.empty()) {
+    std::vector<std::string> platform_extensions_vec;
+    std::string platform_ext = DriverEGL::GetPlatformExtensions();
+    base::SplitString(platform_ext, ' ', &platform_extensions_vec);
+
+    std::vector<std::string> client_extensions_vec;
+    std::string client_ext = DriverEGL::GetClientExtensions();
+    base::SplitString(client_ext, ' ', &client_extensions_vec);
+
+    // Filter out extensions from the command line.
+    for (const std::string& disabled_ext : disabled_exts_) {
+      platform_extensions_vec.erase(std::remove(platform_extensions_vec.begin(),
+                                                platform_extensions_vec.end(),
+                                                disabled_ext),
+                                    platform_extensions_vec.end());
+      client_extensions_vec.erase(std::remove(client_extensions_vec.begin(),
+                                              client_extensions_vec.end(),
+                                              disabled_ext),
+                                  client_extensions_vec.end());
+    }
+
+    // Construct filtered extensions string for GL_EXTENSIONS string lookups.
+    filtered_exts_ = JoinString(platform_extensions_vec, " ");
+    if (!platform_extensions_vec.empty() && !client_extensions_vec.empty())
+      filtered_exts_ += " ";
+    filtered_exts_ += JoinString(client_extensions_vec, " ");
+  }
+}
+
+const char* RealEGLApi::eglQueryStringFn(EGLDisplay dpy, EGLint name) {
+  if (!filtered_exts_.empty() && name == EGL_EXTENSIONS) {
+    return filtered_exts_.c_str();
+  }
+  return EGLApiBase::eglQueryStringFn(dpy, name);
 }
 
 TraceEGLApi::~TraceEGLApi() {