Make EXT_texture_storage enableable.

src/libANGLE/Caps.cpp

@@ -642,7 +642,7 @@ const ExtensionInfoMap &GetExtensionInfoMap()
         map["GL_EXT_sRGB"] = enableableExtension(&Extensions::sRGB);
         map["GL_ANGLE_depth_texture"] = esOnlyExtension(&Extensions::depthTextures);
         map["GL_OES_depth32"] = esOnlyExtension(&Extensions::depth32);
-        map["GL_EXT_texture_storage"] = esOnlyExtension(&Extensions::textureStorage);
+        map["GL_EXT_texture_storage"] = enableableExtension(&Extensions::textureStorage);
         map["GL_OES_texture_npot"] = enableableExtension(&Extensions::textureNPOT);
         map["GL_EXT_draw_buffers"] = enableableExtension(&Extensions::drawBuffers);
         map["GL_EXT_texture_filter_anisotropic"] = enableableExtension(&Extensions::textureFilterAnisotropic);

src/libANGLE/renderer/null/ContextNULL.cpp

@@ -78,6 +78,7 @@ ContextNULL::ContextNULL(const gl::ContextState &state, AllocationTrackerNULL *a
     mExtensions.debugMarker            = true;
     mExtensions.translatedShaderSource = true;
 
+    mExtensions.textureStorage             = true;
     mExtensions.rgb8rgba8 = true;
     mExtensions.textureCompressionDXT1     = true;
     mExtensions.textureCompressionDXT3     = true;

src/tests/gl_tests/WebGLCompatibilityTest.cpp

@@ -482,6 +482,47 @@ TEST_P(WebGLCompatibilityTest, EnablePixelBufferObjectExtensions)
     }
 }
 
+// Test enabling the GL_EXT_texture_storage extension
+TEST_P(WebGLCompatibilityTest, EnableTextureStorage)
+{
+    EXPECT_FALSE(extensionEnabled("GL_EXT_texture_storage"));
+
+    GLTexture texture;
+    glBindTexture(GL_TEXTURE_2D, texture);
+
+    GLint result;
+    glGetTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_IMMUTABLE_FORMAT, &result);
+    if (getClientMajorVersion() >= 3)
+    {
+        EXPECT_GL_NO_ERROR();
+    }
+    else
+    {
+        EXPECT_GL_ERROR(GL_INVALID_ENUM);
+    }
+
+    if (extensionRequestable("GL_EXT_texture_storage"))
+    {
+        glRequestExtensionANGLE("GL_EXT_texture_storage");
+        EXPECT_GL_NO_ERROR();
+        EXPECT_TRUE(extensionEnabled("GL_EXT_texture_storage"));
+
+        glGetTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_IMMUTABLE_FORMAT, &result);
+        EXPECT_GL_NO_ERROR();
+
+        const GLenum alwaysAcceptableFormats[] = {
+            GL_ALPHA8_EXT, GL_LUMINANCE8_EXT, GL_LUMINANCE8_ALPHA8_EXT,
+        };
+        for (const auto &acceptableFormat : alwaysAcceptableFormats)
+        {
+            GLTexture localTexture;
+            glBindTexture(GL_TEXTURE_2D, localTexture);
+            glTexStorage2DEXT(GL_TEXTURE_2D, 1, acceptableFormat, 1, 1);
+            EXPECT_GL_NO_ERROR();
+        }
+    }
+}
+
 // Test enabling the GL_OES_mapbuffer and GL_EXT_map_buffer_range extensions
 TEST_P(WebGLCompatibilityTest, EnableMapBufferExtensions)
 {