Disable TrackStateWhenSwitchingFocusedFrames on all platforms.

The test was disabled on chromeOS, this cl disables the test on other
platforms as well. flakiness dashboard:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=interactive_ui_tests%20(with%20patch)&tests=SitePerProcessTextInputManagerTest.TrackStateWhenSwitchingFocusedFrames

TBR=wjmaclean@chromium.org
NOTRY=TRUE

Bug: 704994
Change-Id: If7b9f6662d7b35fcfc0b9cacec2d215baccfb928
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1759686Reviewed-by: Sahel Sharify <sahel@chromium.org>
Commit-Queue: Sahel Sharify <sahel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688178}

chrome/browser/site_isolation/site_per_process_text_input_browsertest.cc

@@ -440,16 +440,9 @@ class SitePerProcessTextInputManagerTest : public InProcessBrowserTest {
 // creates a sequence of tab presses and verifies that after each key press, the
 // TextInputState.value reflects that of the focused input, i.e., the
 // TextInputManager is correctly tracking TextInputState across frames.
-// Flaky on chromeOS; https://crbug.com/704994.
-#if defined(OS_CHROMEOS)
-#define MAYBE_TrackStateWhenSwitchingFocusedFrames \
-  DISABLED_TrackStateWhenSwitchingFocusedFrames
-#else
-#define MAYBE_TrackStateWhenSwitchingFocusedFrames \
-  TrackStateWhenSwitchingFocusedFrames
-#endif
+// Flaky on ChromeOS, Linux, Mac, and Windows; https://crbug.com/704994.
 IN_PROC_BROWSER_TEST_F(SitePerProcessTextInputManagerTest,
-                       MAYBE_TrackStateWhenSwitchingFocusedFrames) {
+                       DISABLED_TrackStateWhenSwitchingFocusedFrames) {
   CreateIframePage("a(a,b,c(a,b,d(e, f)),g)");
   std::vector<std::string> values{
       "main",     "node_a",   "node_b",     "node_c",     "node_c_a",