Improve NTP browser test error messages

This test fails with LayoutNG's flexbox implementation and I'm trying to
figure out why.

As is, when it fails on the bots, it says the following, whose "Actual"
is uninformative.

 [12496:12496:0214/021305.769266:ERROR:CONSOLE(565)] "Refused to frame 'https://www.chromium.org/' because it violates the following Content Security Policy directive: "child-src chrome-search://most-visited/ https://*.google.com/". Note that 'frame-src' was not explicitly set, so 'child-src' is used as a fallback.
 ", source: chrome-search://local-ntp/doodles.js (565)
 ../../chrome/browser/ui/search/local_ntp_doodle_browsertest.cc:1438: Failure
 Value of: GetDimension(active_tab, searchbox(), "top")

 Expected: is equal to 474
   Actual: 8-byte object <01-00 00-00 26-01 00-00>
 Stack trace:
 #0 0x558beae4a9fe LocalNTPDoodleTest_ShouldMoveFakeboxWhenIframeResized_Test::RunTestOnMainThread()

Change-Id: I0e9a0029ac8f04ca21b7df934cff4e052896e413
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2057639Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: David Grogan <dgrogan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742434}

chrome/browser/ui/search/local_ntp_doodle_browsertest.cc

@@ -1413,10 +1413,11 @@ IN_PROC_BROWSER_TEST_F(LocalNTPDoodleTest, ShouldMoveFakeboxWhenIframeResized) {
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUINewTabURL));
 
   // Initial dimensions are correct:
-  EXPECT_THAT(GetDimension(active_tab, searchbox(), "top"),
+  EXPECT_THAT(*GetDimension(active_tab, searchbox(), "top"),
               Eq(kSearchboxTopPx));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "width"), Eq(400));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "height"),
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "width"),
+              Eq(400));
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "height"),
               Eq(220));
 
   // Trigger resize. The duration parameter is left untested, since that would
@@ -1434,11 +1435,11 @@ IN_PROC_BROWSER_TEST_F(LocalNTPDoodleTest, ShouldMoveFakeboxWhenIframeResized) {
                                      )js"));
 
   // Fakebox is now 180px lower, with the iframe larger, as requested.
-  EXPECT_THAT(GetDimension(active_tab, searchbox(), "top"),
+  EXPECT_THAT(*GetDimension(active_tab, searchbox(), "top"),
               Eq(kSearchboxTopPx + 180));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "width"),
-              Eq(GetDimension(active_tab, "logo", "width")));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "height"),
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "width"),
+              Eq(*GetDimension(active_tab, "logo", "width")));
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "height"),
               Eq(400));
 
   ASSERT_TRUE(content::ExecuteScript(active_tab,
@@ -1452,10 +1453,11 @@ IN_PROC_BROWSER_TEST_F(LocalNTPDoodleTest, ShouldMoveFakeboxWhenIframeResized) {
                                      )js"));
 
   // Back to the original dimensions now.
-  EXPECT_THAT(GetDimension(active_tab, searchbox(), "top"),
+  EXPECT_THAT(*GetDimension(active_tab, searchbox(), "top"),
               Eq(kSearchboxTopPx));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "width"), Eq(400));
-  EXPECT_THAT(GetDimension(active_tab, "logo-doodle-iframe", "height"),
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "width"),
+              Eq(400));
+  EXPECT_THAT(*GetDimension(active_tab, "logo-doodle-iframe", "height"),
               Eq(220));
 }