Use a mocked compositor for unit tests

content/test/browser_test_base.cc

Index: content/test/browser_test_base.cc
diff --git a/content/test/browser_test_base.cc b/content/test/browser_test_base.cc
index 57ca1428c3bfc3a386fac1d1ad08fa127d166f7e..1e9441f3c706f088ac7e1a390ca2156650833f4b 100644
--- a/content/test/browser_test_base.cc
+++ b/content/test/browser_test_base.cc
@@ -8,14 +8,26 @@
 #include "base/task.h"
 #include "content/common/main_function_params.h"
 #include "sandbox/src/dep.h"
+#include "ui/gfx/gl/gl_switches.h"
 
 #if defined(OS_MACOSX)
 #include "base/mac/mac_util.h"
 #include "base/system_monitor/system_monitor.h"
 #endif
 
+#if defined(VIEWS_COMPOSITOR)
+#include "ui/gfx/compositor/compositor.h"
+#include "ui/gfx/compositor/test_compositor.h"
+#endif
+
 extern int BrowserMain(const MainFunctionParams&);
 
+#if defined(VIEWS_COMPOSITOR)
+static ui::Compositor* TestCreateCompositor(ui::CompositorDelegate* owner) {
+  return new ui::TestCompositor(owner);
+}
+#endif
+
 BrowserTestBase::BrowserTestBase() {
 #if defined(OS_MACOSX)
   base::mac::SetOverrideAmIBundled(true);
@@ -27,19 +39,33 @@ BrowserTestBase::~BrowserTestBase() {
 }
 
 void BrowserTestBase::SetUp() {
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+
+  // Use MesaGL as the GL implementation, as desktopgl/egl is not present on
+  // test bots yet.
+  EXPECT_TRUE(!command_line->HasSwitch(switches::kUseGL));
+  command_line->AppendSwitchASCII(switches::kUseGL,
+                                  gfx::kGLImplementationOSMesaName);
+
   SandboxInitWrapper sandbox_wrapper;
-  MainFunctionParams params(*CommandLine::ForCurrentProcess(),
-                            sandbox_wrapper,
-                            NULL);
+  MainFunctionParams params(*command_line, sandbox_wrapper, NULL);
   params.ui_task =
       NewRunnableMethod(this, &BrowserTestBase::ProxyRunTestOnMainThreadLoop);
 
+#if defined(VIEWS_COMPOSITOR)
+  // Use a mock compositor that noops draws.
+  ui::Compositor::set_compositor_factory_for_testing(&TestCreateCompositor);
+#endif
+
   SetUpInProcessBrowserTestFixture();
   BrowserMain(params);
   TearDownInProcessBrowserTestFixture();
 }
 
 void BrowserTestBase::TearDown() {
+#if defined(VIEWS_COMPOSITOR)
+  ui::Compositor::set_compositor_factory_for_testing(NULL);
+#endif
 }
 
 void BrowserTestBase::ProxyRunTestOnMainThreadLoop() {