Upload textures through GPU path to non-8-bit color formats won't work in WebGL2

This is because we use copyTexImage to do the GPU to GPU copying, but in ES3
it is limited that source/destination color format component sizes have to match.

We can lift this limitation once we implement a different path where shaders are
used to do the copying instead of copyTexImage.

BUG=429053
TEST=gpu_bots
R=kbr@chromium.org,cwallez@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2040773002
Cr-Commit-Position: refs/heads/master@{#398230}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -78,45 +78,6 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
     self.Fail('deqp/functional/gles3/multisample.html',
         ['amd'], bug=617290)
 
-    # Failing because the tests are using invalid combinations of source and
-    # destination formats, see https://github.com/KhronosGroup/WebGL/issues/1628
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgb565-rgb-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgb565-rgb-unsigned_short_5_6_5.html',
-        bug=483282)
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgb5_a1-rgba-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgb5_a1-rgba-unsigned_short_5_5_5_1.html',
-        bug=483282)
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgba4-rgba-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/webgl_canvas/' +
-        'tex-2d-rgba4-rgba-unsigned_short_4_4_4_4.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgb565-rgb-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgb565-rgb-unsigned_short_5_6_5.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgb5_a1-rgba-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgb5_a1-rgba-unsigned_short_5_5_5_1.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgba4-rgba-unsigned_byte.html',
-        bug=483282)
-    self.Fail('conformance2/textures/canvas/' +
-        'tex-2d-rgba4-rgba-unsigned_short_4_4_4_4.html',
-        bug=483282)
-
     # Windows only.
 
     self.Fail('deqp/functional/gles3/vertexarrays.html',

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp

@@ -461,6 +461,21 @@ bool WebGL2RenderingContextBase::checkAndTranslateAttachments(const char* functi
     return true;
 }
 
+bool WebGL2RenderingContextBase::canUseTexImageCanvasByGPU(GLint internalformat, GLenum type)
+{
+    switch (internalformat) {
+    case GL_RGB565:
+    case GL_RGBA4:
+    case GL_RGB5_A1:
+        // FIXME: ES3 limitation that CopyTexImage with sized internalformat,
+        // component sizes have to match the source color format.
+        return false;
+    default:
+        break;
+    }
+    return WebGLRenderingContextBase::canUseTexImageCanvasByGPU(internalformat, type);
+}
+
 void WebGL2RenderingContextBase::invalidateFramebuffer(GLenum target, const Vector<GLenum>& attachments)
 {
     if (isContextLost())

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h

@@ -271,6 +271,8 @@ protected:
     WebGLBuffer* validateBufferDataTarget(const char* functionName, GLenum target) override;
     bool validateBufferDataUsage(const char* functionName, GLenum usage) override;
 
+    bool canUseTexImageCanvasByGPU(GLint internalformat, GLenum type) override;
+
     void removeBoundBuffer(WebGLBuffer*) override;
 
     void resetUnpackParameters() override;

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h

@@ -792,7 +792,7 @@ protected:
     // Copy from the canvas element directly to the texture via the GPU, without a read-back to system memory.
     void texImageCanvasByGPU(TexImageByGPUType, WebGLTexture*, GLenum target, GLint level,
         GLint internalformat, GLenum type, GLint xoffset, GLint yoffset, GLint zoffset, HTMLCanvasElement*);
-    bool canUseTexImageCanvasByGPU(GLint internalformat, GLenum type);
+    virtual bool canUseTexImageCanvasByGPU(GLint internalformat, GLenum type);
 
     virtual WebGLImageConversion::PixelStoreParams getPackPixelStoreParams();
     virtual WebGLImageConversion::PixelStoreParams getUnpackPixelStoreParams(TexImageDimension);