Re-enable GPU Rasterization for content with any author defined viewport.

BUG=591179

Review-Url: https://codereview.chromium.org/2097413003
Cr-Commit-Position: refs/heads/master@{#402702}

third_party/WebKit/Source/core/dom/ViewportDescription.cpp

@@ -257,9 +257,7 @@ void ViewportDescription::reportMobilePageStats(const LocalFrame* mainFrame) con
 
 bool ViewportDescription::matchesHeuristicsForGpuRasterization() const
 {
-    return maxWidth == Length(DeviceWidth)
-        && minZoom == 1.0
-        && minZoomIsExplicit;
+    return isSpecifiedByAuthor();
 }
 
 } // namespace blink

third_party/WebKit/Source/web/tests/ViewportTest.cpp

@@ -2786,8 +2786,14 @@ TEST_F(ViewportTest, viewportLimitsAdjustedForNoUserScaleControl)
 
 TEST_F(ViewportTest, viewportTriggersGpuRasterization)
 {
-    registerMockedHttpURLLoad("viewport/viewport-gpu-rasterization.html");
     FrameTestHelpers::WebViewHelper webViewHelper;
+
+    registerMockedHttpURLLoad("viewport/viewport-gpu-rasterization-disabled-without-viewport.html");
+    webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-gpu-rasterization-disabled-without-viewport.html", true, nullptr, nullptr, nullptr, setViewportSettings);
+    webViewHelper.webView()->resize(WebSize(640, 480));
+    EXPECT_FALSE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+
+    registerMockedHttpURLLoad("viewport/viewport-gpu-rasterization.html");
     webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-gpu-rasterization.html", true, nullptr, nullptr, nullptr, setViewportSettings);
     webViewHelper.webView()->resize(WebSize(640, 480));
     EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
@@ -2797,25 +2803,30 @@ TEST_F(ViewportTest, viewportTriggersGpuRasterization)
     webViewHelper.webView()->resize(WebSize(640, 480));
     EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
 
-    registerMockedHttpURLLoad("viewport/viewport-inferred-values-do-not-trigger-gpu-rasterization.html");
-    webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-inferred-values-do-not-trigger-gpu-rasterization.html", true, nullptr, nullptr, nullptr, setViewportSettings);
-    webViewHelper.webView()->resize(WebSize(640, 480));
-    EXPECT_FALSE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
-
     registerMockedHttpURLLoad("viewport/viewport-1.html");
     webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-1.html", true, nullptr, nullptr, nullptr, setViewportSettings);
     webViewHelper.webView()->resize(WebSize(640, 480));
-    EXPECT_FALSE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+    EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
 
     registerMockedHttpURLLoad("viewport/viewport-15.html");
     webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-15.html", true, nullptr, nullptr, nullptr, setViewportSettings);
     webViewHelper.webView()->resize(WebSize(640, 480));
-    EXPECT_FALSE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+    EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
 
     registerMockedHttpURLLoad("viewport/viewport-130.html");
     webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-130.html", true, nullptr, nullptr, nullptr, setViewportSettings);
     webViewHelper.webView()->resize(WebSize(640, 480));
-    EXPECT_FALSE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+    EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+
+    registerMockedHttpURLLoad("viewport/viewport-legacy-handheldfriendly.html");
+    webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-legacy-handheldfriendly.html", true, nullptr, nullptr, nullptr, setViewportSettings);
+    webViewHelper.webView()->resize(WebSize(640, 480));
+    EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
+
+    registerMockedHttpURLLoad("viewport/viewport-legacy-mobileoptimized.html");
+    webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-legacy-handheldfriendly.html", true, nullptr, nullptr, nullptr, setViewportSettings);
+    webViewHelper.webView()->resize(WebSize(640, 480));
+    EXPECT_TRUE(webViewHelper.webViewImpl()->matchesHeuristicsForGpuRasterizationForTesting());
 }
 
 class ConsoleMessageWebFrameClient : public FrameTestHelpers::TestWebFrameClient {

third_party/WebKit/Source/web/tests/data/viewport/viewport-gpu-rasterization-disabled-without-viewport.html

+<head>
+    <title>No viewport tag, no GPU rasterization trigger</title>
+</head>
+<body></body>

third_party/WebKit/Source/web/tests/data/viewport/viewport-inferred-values-do-not-trigger-gpu-rasterization.html

-<head>
-    <title>Viewport that triggers GPU rasterization</title>
-    <meta name="viewport" content="width=device-width, minimum-scale=yes, initial-scale=yes, user-scalable=yes">
-</head>
-<body></body>