Backwards compatibility with HistoryItems with old page scale (attempt 2).

Given the semantic change in page scale, users upgrading from M18 would
find their existing tabs all zoomed in at a weird scroll offset.  Add
some more backwards compatibility cruft to compensate.

Fix GlueSerializeTest to expect the new semantics.

BUG=175807


Review URL: https://chromiumcodereview.appspot.com/12313117

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@184591 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 28 insertions, 4 deletions

diff --git a/webkit/glue/glue_serialize.cc b/webkit/glue/glue_serialize.cc
index e9d3ae4..cfe9330 100644
--- a/webkit/glue/glue_serialize.cc
+++ b/webkit/glue/glue_serialize.cc
@@ -17,6 +17,7 @@
 #include "third_party/WebKit/Source/Platform/chromium/public/WebVector.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebHistoryItem.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebSerializedScriptValue.h"
+#include "ui/gfx/screen.h"
 #include "webkit/base/file_path_string_conversions.h"
 
 using WebKit::WebData;
@@ -456,11 +457,23 @@ WebHistoryItem ReadHistoryItem(
   }
 
 #if defined(OS_ANDROID)
-  // Now-unused values that shipped in this version of Chrome for Android when
-  // it was on a private branch.
   if (obj->version == 11) {
+    // Now-unused values that shipped in this version of Chrome for Android when
+    // it was on a private branch.
     ReadReal(obj);
     ReadBoolean(obj);
+
+    // In this version, pageScaleFactor included deviceScaleFactor and scroll
+    // offsets were premultiplied by pageScaleFactor.
+    if (item.pageScaleFactor()) {
+      if (include_scroll_offset)
+        item.setScrollOffset(
+            WebPoint(item.scrollOffset().x / item.pageScaleFactor(),
+                     item.scrollOffset().y / item.pageScaleFactor()));
+      item.setPageScaleFactor(item.pageScaleFactor() /
+          gfx::Screen::GetNativeScreen()->GetPrimaryDisplay()
+              .device_scale_factor());
+    }
   }
 #endif
 
diff --git a/webkit/glue/glue_serialize_unittest.cc b/webkit/glue/glue_serialize_unittest.cc
index 250dceac..b03fc53 100644
--- a/webkit/glue/glue_serialize_unittest.cc
+++ b/webkit/glue/glue_serialize_unittest.cc
@@ -10,6 +10,7 @@
 #include "third_party/WebKit/Source/Platform/chromium/public/WebHTTPBody.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebPoint.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebVector.h"
+#include "ui/gfx/screen.h"
 #include "webkit/base/file_path_string_conversions.h"
 #include "webkit/glue/glue_serialize.h"
 #include "webkit/glue/web_io_operators.h"
@@ -108,6 +109,16 @@ class GlueSerializeTest : public testing::Test {
   void HistoryItemExpectBaseDataEqual(const WebHistoryItem& a,
                                       const WebHistoryItem& b,
                                       int version) {
+    float expectedPageScaleFactor = a.pageScaleFactor();
+    WebPoint expectedScrollOffset = a.scrollOffset();
+#if defined(OS_ANDROID)
+    if (version == 11) {
+      expectedScrollOffset.x /= a.pageScaleFactor();
+      expectedScrollOffset.y /= a.pageScaleFactor();
+      expectedPageScaleFactor /= gfx::Screen::GetNativeScreen()
+          ->GetPrimaryDisplay().device_scale_factor();
+    }
+#endif
     EXPECT_EQ(string16(a.urlString()), string16(b.urlString()));
     EXPECT_EQ(string16(a.originalURLString()), string16(b.originalURLString()));
     EXPECT_EQ(string16(a.target()), string16(b.target()));
@@ -115,12 +126,12 @@ class GlueSerializeTest : public testing::Test {
     EXPECT_EQ(string16(a.title()), string16(b.title()));
     EXPECT_EQ(string16(a.alternateTitle()), string16(b.alternateTitle()));
     EXPECT_EQ(a.lastVisitedTime(), b.lastVisitedTime());
-    EXPECT_EQ(a.scrollOffset(), b.scrollOffset());
+    EXPECT_EQ(expectedScrollOffset, b.scrollOffset());
     EXPECT_EQ(a.isTargetItem(), b.isTargetItem());
     EXPECT_EQ(a.visitCount(), b.visitCount());
     EXPECT_EQ(string16(a.referrer()), string16(b.referrer()));
     if (version >= 11)
-      EXPECT_EQ(a.pageScaleFactor(), b.pageScaleFactor());
+      EXPECT_EQ(expectedPageScaleFactor, b.pageScaleFactor());
     if (version >= 9)
       EXPECT_EQ(a.itemSequenceNumber(), b.itemSequenceNumber());
     if (version >= 6)