[Webgl-blink] Add test function to force fail the webgl-context.

In order to test whether the  GPU(Vendor,Renderer,Driver info)
is getting fetched properly when creating the context,
we need to provide a function to force fail the context on 
creation, which can be used by test-runner. 

This patch implements the forceNextWebGLContextCreationToFail.
Test-runner can use this further.

test-runner-cl which uses forceNextWebGLContextCreationToFail
@https://codereview.chromium.org/706193003/

BUG=412440

Review URL: https://codereview.chromium.org/703903002

git-svn-id: svn://svn.chromium.org/blink/trunk@185272 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/html/canvas/WebGLRenderingContext.cpp

@@ -61,6 +61,8 @@
 
 namespace blink {
 
+static bool shouldFailContextCreationForTesting = false;
+
 PassOwnPtrWillBeRawPtr<WebGLRenderingContext> WebGLRenderingContext::create(HTMLCanvasElement* canvas, WebGLContextAttributes* attrs)
 {
     Document& document = canvas->document();
@@ -87,7 +89,8 @@ PassOwnPtrWillBeRawPtr<WebGLRenderingContext> WebGLRenderingContext::create(HTML
     blink::WebGraphicsContext3D::Attributes attributes = attrs->attributes(document.topDocument().url().string(), settings, 1);
     blink::WebGLInfo glInfo;
     OwnPtr<blink::WebGraphicsContext3D> context = adoptPtr(blink::Platform::current()->createOffscreenGraphicsContext3D(attributes, 0, &glInfo));
-    if (!context) {
+    if (!context || shouldFailContextCreationForTesting) {
+        shouldFailContextCreationForTesting = false;
         String statusMessage("Could not create a WebGL context for VendorInfo = ");
         statusMessage.append(glInfo.vendorInfo);
         statusMessage.append(", RendererInfo = ");
@@ -182,4 +185,9 @@ void WebGLRenderingContext::trace(Visitor* visitor)
     WebGLRenderingContextBase::trace(visitor);
 }
 
+void WebGLRenderingContext::forceNextWebGLContextCreationToFail()
+{
+    shouldFailContextCreationForTesting = true;
+}
+
 } // namespace blink

third_party/WebKit/Source/core/html/canvas/WebGLRenderingContext.h

@@ -35,6 +35,7 @@ class WebGLRenderingContext final : public WebGLRenderingContextBase, public Scr
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassOwnPtrWillBeRawPtr<WebGLRenderingContext> create(HTMLCanvasElement*, WebGLContextAttributes*);
+    static void forceNextWebGLContextCreationToFail();
     virtual ~WebGLRenderingContext();
 
     virtual unsigned version() const override { return 1; }

third_party/WebKit/Source/web/WebViewImpl.cpp

@@ -61,6 +61,7 @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLTextAreaElement.h"
+#include "core/html/canvas/WebGLRenderingContext.h"
 #include "core/html/ime/InputMethodContext.h"
 #include "core/inspector/InspectorController.h"
 #include "core/loader/DocumentLoader.h"
@@ -4500,4 +4501,9 @@ bool WebViewImpl::shouldDisableDesktopWorkarounds()
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
+void WebViewImpl::forceNextWebGLContextCreationToFail()
+{
+    WebGLRenderingContext::forceNextWebGLContextCreationToFail();
+}
+
 } // namespace blink

third_party/WebKit/Source/web/WebViewImpl.h

@@ -508,6 +508,8 @@ public:
 
     virtual void setTopControlsLayoutHeight(float) override;
 
+    virtual void forceNextWebGLContextCreationToFail() override;
+
 private:
     void didUpdateTopControls();
     void setTopControlsContentOffset(float);

third_party/WebKit/public/web/WebView.h

@@ -493,6 +493,10 @@ public:
 
     // Testing functionality for TestRunner ---------------------------------
 
+    // Force the webgl context to fail so that webglcontextcreationerror
+    // event gets generated/tested.
+    virtual void forceNextWebGLContextCreationToFail() = 0;
+
 protected:
     ~WebView() {}
 };